US3052786A

US3052786A - Electrical switch

Info

Publication number: US3052786A
Application number: US860212A
Authority: US
Inventors: Ronald J Bertling
Original assignee: McGraw Edison Co
Current assignee: McGraw Edison Co
Priority date: 1959-12-17
Filing date: 1959-12-17
Publication date: 1962-09-04
Anticipated expiration: 1979-09-04

Description

Sept. 4, 1962 R. J. BERTLING ELECTRICAL SWITCH 4 Sheets-Sheet 1 Filed Dec. 17, 1959 Cj J E Sept. 4, 1962 R. J. BERTLING 3,052,735

ELECTRICAL SWITCH Filed Dec. 1'7, 1959 4 Sheets-Sheet 2 IN VEN TOR. Fomzid J Berlzgy Sept. 4, 1962 R. J. BERTLING ELECTRICAL SWITCH 4 Sheets-Sheet 5 Filed D60. 17, 1959 P 1962 R. J. BERTLING 3,052,786

ELECTRICAL SWITCH Filed Dec. 17, 1959 4 Sheets-Sheet 4 a4 96 l 5 as 704 I l Ill 50 707 as j? 1. I j: ,/&56

INVENTOR. RomzZd J Bertlny United States Patent 3,052,786 ELECTRICAL SWITCH Ronald J. Bertling, South Milwaukee, Wis., assignor to McGraw-Edison Company, Milwaukee, Wis, a corporation of Delaware Filed Dec. 17, 1959, Ser. No. 860,212 12 Claims. (Cl. 200-170) This invention relates to electrical switches and, more particularly, to contact structure for electrical disconnect switches.

In electrical disconnect switches, wherein a switch blade is pivoted into and out of engagement with a stationary contact jaw, it is necessary that the contact pressure be sufliciently high to provide good electrical contact. On the other hand, excessively high contact pressure tends to impede movement of the switch blade into and out of engagement with the contact jaw which causes excessive wear.

It is an object of the invention to provide a high pressure contact jaw for disconnect switches wherein contact pressure is relieved during movement of the switch blade into and out of its closed position.

It is another object of the invention to provide a high pressure contact jaw which does not inhibit the opening or closing movement of the contact blade.

It is a further object of the invention to provide a pivotable contact jaw which is snap acting into closed position thereby tending to be held in said closed position against the effects of electrical or other external forces.

It is a still further object of the invention to provide a rotatable contact jaw whose limit stops are completely enclosed so that its operation cannot be effected by the collection of ice.

These and other objects and advantages of the invention will become more apparent from the detailed description of the invention taken with the accompanying drawings in which:

FIG. 1 shows an elevational view of a disconnect switch embodying the instant invention;

FIG. 2 shows a top plan view of the disconnect switch shown in FIG. 1;

FIG. 3 is a top view of the pivotal contact jaw showing each of its alternate positions;

PEG. 4 is a view taken along lines 44 of FIG. 3;

FIG. 5 is a view taken along lines 55 of FIG. 3;

FIG. 6 is a view taken along lines 66 of FIG. 4;

FIG. 7 shows the developed cam surface upon which the contact fingers of the preferred embodiment of the invention pivot;

FIG. 8 is a partial sectional view of an alternate em bodiment of the instant invention;

PEG. 9 is a view taken along lines 9-9 of FIG. 8; and

FIG. 10 is a view taken along lines 1018 of FIG. 9.

In general terms the invention comprises an electrical switch having a movable switch blade, stationary contact fingers engageable by said switch blade, contact spring means, and means for relieving the contact spring pressure as the switch blade moves out of engagement with said stationary contacts and for re-establishing said contact pressure upon the ire-engagement thereof.

According to a more specific aspect of the invention, the stationary contact means includes opposed contact fingers pivotally mounted on a cam surface for movement between first and second positions as the switch blade moves through the initial portion of its opening operation. The cam surfaces are so formed that such pivotal movement operates to displace a portion of each contact finger away from its associated contact pressure spring.

ice

Similarly when the switch blade moves through the last portion of its closing operation, the contact fingers are returned to their initial position whereby contact pressure is re-established.

FIG. 1 illustrates a rotating insulator type sidebreak disconnect switch incorporating a preferred embodiment of the instant invention and designated generally by the reference numeral 11. Switch 11 is shown mounted on a horizontal channel member 12 which supports a vertical stationary insulator 14 and a spaced apart rotatable insulator 16 which is mounted on a bearing 17 for rotation about a vertical axis under the action of a lever 18 and supported on the channel 12 by a bearing mount 19.

A contact blade mounting bracket 20 and clamping assembly 21 support a contact blade 22 on the upper end of insulator 16 for rotation in a horizontal plane into and out of engagement with stationary contact structure 24 mounted on the upper end of stationary insulator 14 by a conductive contact support bracket 26.

The stationary contact structure 24 includes a pair of contact fingers 28 each of which is pivotally mounted on a bearing assembly 30 and each carries a pair of leaftype contact spring assemblies 32 for providing contact pressure when the switch is in the closed position shown by full lines in FIG. 2.

In order to open the switch from its closed position shown by full lines in FIGS. 1 and 2, operating lever 17 is rotated in a clockwise direction as viewed in FIG. 2 from its full to its dashed position by any suitable switch operating means which is not shown but which is well known in the art. This rotates insulator 16 through a corresponding angle to move switch arm 22 out of engagement with contact jaws 28 and through an approximately degree angle to its dashed position. As contact blade 22 rotates through the initial portion of this angle, its high pressure engagement with contact fingers 28 causes them to rotate from their position shown by full lines in FIG. 2 to their dashed position. Further rotation of switch blade 22 toward its fully open position disengages it from contact fingers 28.

An arcing horn assembly comprising a movable arcing blade 38 carried by contact blade 22 and a stationary arcing horn 44} carried by the stationary support bracket 26 is provided so that the contact fingers 28 and the contact tip of switch blade 22 will not be subjected to arcing upon the opening or the closing of the switch 11.

The swiveling action of stationary contact assembly 24 described above, can best be seen by reference to FIG. 3 As contact blade 22 begins rotating from its closed position shown by full lines the frictional force resulting from the high pressure engagement between contact fingers 28 sets up a counterclockwise torque in said contact fingers causing them to rotate on bearing assembly 30 until they reach the position shown by dashed lines whereupon further motion is arrested by an internal stop which will be discussed in greater detail hereinafter. Contact blade 22 thereafter continues to its fully open position. Contact finger support arms 29 extending laterally from each contact finger engage when the switch is open to prevent collapse of the stationary contact assembly 24. When the switch 11 is reclosed contact blade 22 is rotated to the position shown by dashed lines in FIG. 3 whereupon it engages the contact finger support arms 29 which rotates the contact fingers 28 in a clockwise direction from their dotted to their full position whereupon they engage a second internal stop.

The invention comprises a means for relieving the contact pressure as contact blade 22 moves from its full to its dashed position shown in FIG. 3 and for re-establishing it upon movement in the opposite direction so that the amount of torque on operating levers 17, necessary to move contact blade 22 into and out of engagement with contact fingers 28, is considerably reduced. In the preferred embodiment of the invention shown in FIGS. 4, and 6, the pressure relief means comprises a cam surface upon which the contact fingers pivot so that as they move between their closed and open positions their pivoted ends 44 are allowed to move closer together thereby relaxing contact springs 32 and relieving the contact pressure.

As seen in FIGS. 4 and 5, the contact springs 32 are loaded by means of tie bars 50 which extend through opposed leaf spring assemblies on each of the contact fingers 28 and which are retained in bearing relation with said leaf spring assemblies by means of retainer pins 52 which extend transversely through each end. One end of each of the longest leaf springs 54 is perforated for embracing an anchoring pin 56 integral with and extending laterally from each of the contact fingers 28. A shoulder 58 on pin 56 provides a pressure pad at one end of leaf spring 54 while the other end thereof engages a second pressure pad 60 on the opposite side of tie rod 50 and integral with contact fingers 28.

It can be seen from FIG. 4 that when the switch is in its closed position the distance between corresponding pressure pads on each of the contact fingers 28 is greater than the distance between the pins 52 on each end of the tie bars 50 plus the thickness of leaf spring assemblies 32. Thus, the ends of said leaf spring assemblies are bowed outwardly to provide contact pressure at each of the

pressure pads

58 and 60.

Referring now to FIGS. 4, 5 and 6, the bearing assembly 30 is shown to include an annular housing 61 which is fixedly mounted to bracket 26 by a conductive base portion 62 and which has a pair of substantially coaxial, in-

wardly extending bearing posts 63 integral therewith. The pivotal end 58 of each of the contact fingers 28 is provided with an annular bearing portion 65 which are disposed in a coaxial relationship on the interior of housing 60. A cam surface 59 is for-med on diametrically opposite edges of each of the bearing portions 65 and each of said cam surfaces is in engagement with one of the bearing posts 63. The development of cam surfaces 59 is shown in FIG. 7 to have a shallow portion 66, a depressed portion 68 and a barrier portion 69. It can be seen from FIGS. 4 and 5 that opposed cam surfaces 59 in each of the contact fingers 28 are formed with corresponding portions in a symmetrical relationship.

When the switch is in its closed position, as shown in FIG. 4, bearing posts 63 are in engagement with the shallow portions 66 of each of the cam surfaces 59. The depth of these portions is so chosen that the pivotal ends 44 of contact fingers 28 will be forced a predetermined distance apart. As a result, the distance between pressure pads 58 will be sufficient to hold leaf spring assemblies 32 in a flexed state whereby contact pressure is provided. When the contact jaw assembly is rotated to its open position as shown by the dotted lines in FIG. 3 and in 'FIG. 5, contact fingers 28 will rotate in a counterclockwise direction as shown in FIG. 6 thereby moving the shallow portion 66 of cam surfaces 59 from engagement with bearing posts 63 and moving depressed portions 68 into engagement therewith. Because of the greater depth of depressed portions 68, the pivotal ends 58 of contact fingers 28 are free to move closer together thereby diminishing the spacing between pressure pads 58 so that leaf spring assemblies 3-2 are relaxed. In this manner, the contact pressure between contact fingers 28 and switch blade 22 is diminished.

' I From the foregoing it will be apparent that the contact pressure is greatest when the contact fingers 28 and the switch blade 22 are in their closed position shown in FIG. 4 and by the full lines in FIG. 3 and at a minimum when thecontact'fin gers 28 are in their open position shown in FIG. 5 and by the dashed lines in FIG. 3. As a result relatively little force is required to move switch blade 22 out of and into its engaged position between contact fingers 28, shown by dashed lines in FIG. 3, when the switch 11 is being opened and closed. Also, the amount of force necessary to pivot contact fingers 28 into and out of their closed position shown full in FIG. 3 is only a fraction of the force that would be necessary to close the switch if the contact pressure were to remain constant.

Referring again to FIG. 7 it can be seen that barrier portions 69 of the cam surfaces 59 is raised relative to

portions

66 and 68. Thus, the contact fingers are forced to overcome said barrier portion when the area of engagement with bearing posts 63 change from one of the

portions

66 and 68 to the other. In this manner the contact fingers tend to snap into position as they rotate between their open and closed positions thereby providing a more positive action. In addition, barrier portion 69 tends to prevent the contact fingers from being moved out of the closed position under the influence of short circuit magnetic forces and the like.

Because of the shape of cam surface 59,movement of contact fingers in either direction will be arrested when the concave ends 70 or 71 of said surface engage the hearing posts 63. This eliminates the necessity for external stops to limit the pivotal movement of contact fingers 28, thereby greatly diminishing the danger that ice formation will inhibit the operation of the switch.

The current path from, switch blade 22 to conductive support bracket 26 and through stationary contact structure 24 has a first exchange point between switch blade 22 and contact fingers 28 and a second exchange point between cam surface 59 and bearing posts 63. From FIG. 4 it can be seen that when the switch is in its closed position leaf spring assemblies 32 provide contact pressure for both of these exchange points.

FIGS. 8, 9 and 10 show an alternate embodiment of the invention in which the camsurface is formed in the bearing assembly 82 rather than on the contact fingers. More specifically, assembly 82 is provided with a recess 83 in each of its opposite sides for receiving a hinge pin 84 integral with the ends of contact fingers 86. The cam surface 80 is formed on an undercut portion 87 at the rear of recess 83 and includes an upper portion 88 and a downwardly sloping portion 90.

A horseshoe shaped force transmitting member 92 is disposed circumjacent hinge pin 84 with its rear portion 94 disposed in undercut portion 87 and in engagement with cam surface 80. As seen in FIG. 10 rear portion 94 extends downwardly to form a cam follower 95. Each of the

front corners

96 and 98 of member 92 engages a notch 98 formed in the upper end of an anchor pin 99 which is slidably received through one of a pair Of apertures 100 formed in contact fingers 86 and whose outer ends engage leaf spring assemblies 105.

As seen in FIGS. 9 and 10, the front portion of member 92 is received in a notch 104 out in the front of hinge pin 84 while each of the corners 96 rest on notches 98 formed in the upper ends of anchor pins 100. As a result, memher 92 is locked to contact finger 86 so that it is forced to rotate therewith.

When the switch contacts are in closed position, the cam follower is on the upper portion of cam surface 80 so that its corners 96 are tilted downwardly as shown in FIG. 9. As a result, anchor pins are forced outwardly to flex contact springs 105. When the contact fingers 86 are rotated in a counterclockwise direction as viewed in FIG. 8 and toward open position, cam follower 95 is moved to the lower portion 90 of cam surface 80, thereby releasing the pressure on corners 96 and allowing anchor pins 100 to move upwardly as viewed in FIG. 9 and thereby relax pressure springs 105. Integral stop portions 106 are formed on contact finger 86 for engagement with the face 107 of the rear portion of recess 83 so that the rotational angle of contact finger 86 is limited to the desired value.

While only a few embodiments of the invention have been shown and described, others will become apparent to those skilled in the art once applicants inventive concept is known. Accordingly, it is intended to cover in the appended claims all embodiments that fall within the true spirit of the invention.

I claim:

1. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means engageable by said switch blade when said switch is in its closed position and including opposed contact elements, contact spring means normally urging said contact elements into high pressure engagement with said switch blade, and spring pressure relief means actuable by said switch blade to substantially reduce said contact pressure as said switch blade initiates its pivotal movement toward open position and prior to the disengagement thereof from said contact fingers, said spring pressure relief means also being operative to reestablish said contact pressure as said switch blade completes its movement toward closed position and after the engagement thereof with said contact fingers.

2. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means including opposed contact fingers having contact tip means near one end that are engageable by said switch blade when said switch is in its closed position, contact spring means engaging the outer surfaces of said contact fingers for normafly urging them into high pressure engagement with said switch blade, and spring pressure relief means actuable by said switch blade for moving the other ends of said contact fingers to substantially reduce said contact pressure as said switch blade initiates its pivotal movement toward open position and prior to the disengagement thereof from said contact fingers, said spring pressure relief means also being operative upon movement of said switch blade toward closed position to move said other ends of the contact fingers to their initial positions and thereby re-establish said contact pressure after the re-engagement of said switch blade with said contact tip means.

3. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means engageable by said switch blade when said switch is in its closed position and including opposed contact fingers, cam means, each of said contact fingers being pivotally mounted on said cam means, contact spring means urging said contact fingers toward high pressure engagement with said switch blade, the frictional force generated between said switch blade and said contact fingers operating to pivot said contact fingers on said cam means between a first and a second angular position when said switch blade is pivoted toward open position, said cam means being so arranged that pivotal movement of said contact fingers toward their second angular position is operative to displace portions thereof relative to said contact spring means so that said contact pressure is relieved, movement of said switch blade toward closed position being operative to pivot said contact fingers to their first angular position so that their pivotal ends return to their initial position whereby said contact pressure is re-established.

4. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means engageable by said switch blade when said switch is in its closed position and including opposed contact fingers each pivotally mounted on a bearing member about a common axis that is parallel to the pivotal axis of said switch blade, contact spring means urging said contact fingers into high pressure engagement with said switch blade, the frictional force generated between said switch blade and said contact fingers operating to pivot said contact fingers between first and second angular positions when said switch blade is pivoted toward open position, cam means disposed between said contact fingers and said bearing member so that the pivotal ends of said contact fingers are displaced relative to said contact spring means during pivotal movement toward said second angular position so that said contact pressure is relieved, movement of said switch blade toward closed position being operative to pivot said contact fingers toward their first position whereby said contact pressure is re-established.

5. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means including a pair of opposed contact fingers having contact tip means near one end engageable by said switch blade when the latter is in its closed position, leaf spring means disposed adjacent each of said contact fingers in substantially parallelism therewith and engaging each of the opposite ends thereof for urging said contact fingers into high pressure engagement with said switch blade, tie bar means engaging a central portion of each of said leaf spring means for holding said portions in a fixed spacial relation, pressure relief means for moving the other end of said contact fingers toward each other when said switch blade moves toward open position so that said leaf spring means are relaxed and said contact pressure is relieved, said pressure relief means being operative to move said other ends of said contact fingers toward their initial positions when said switch blade is moved toward its closed position whereby said contact pressure is re-established.

6. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means including a pair of opposed contact fingers having contact tip means near one end engageable by said switch blade when the latter is in its closed position, a bearing member, each of said contact fingers being pivotally mounted near its other end on said bearing member and about a common axis that is substantially parallel to the pivotal axis of said switch blade, leaf spring means disposed adjacent each of said contact fingers in substantial parallelism therewith and engaging each of the opposite ends thereof for urging said contact fingers into high pressure engagement with said switch blade, tie bar means engaging a central portion of each of said leaf spring means for holding said portions in a fixed spacial relation, the frictional force generated between said switch blade and said contact fingers being operative to pivot said contact fingers between first and second angular positions when said switch blade is pivoted toward its open position, cam means disposed between the other end of each contact finger and said bearing member so that said other ends are moved toward each other as said contact fingers pivot toward their second angular positions whereby said leaf spring means are relaxed and said contact pressure is relieved, movement of said switch blade toward closed position being operative to pivot said contact fingers toward their first angular position whereby said contact pressure is re-established.

7. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means including a pair of opposed contact fingers having contact tip means near one end engageable by said switch blade when the latter is in its closed position, a bearing member having a pair of opposed bearing posts, each of said contact fingers being pivotally mounted near its other end on said bearing member and about a common axis that is substantially parallel to the pivotal axis of said switch blade, spring 'means engaging the outside of each of said contact fingers for urging them toward high pressure engagement with said switch blade, the frictional force generated between said switch blade and said contact fingers operating to pivot said contact fingers between first and second angular position when said switch blade is pivoted toward its open position, a cam surface formed on the pivotal end of each contact finger for engagement with said bearing post means, said cam surfaces being so formed that said pivotal ends are moved toward each other as said contact fingers pivot .toward their second, angular positions whereby said contact pressure is relieved, movement of said switch blade toward closed position being operative to pivot said contact fingers toward their first position whereby said contact pressure is re-established.

' 8. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means including a pair of opposed contact fingers having contact tip means near one end engageable by said switch blade when the latter is in its closed position, a bearing member having a pair of opposed bearing posts, each of said contact fingers being pivotally mounted near its other end on one of said bearing posts and about a common axis that is substantially parallel to the pivotal axisof said switch blade, leaf spring means disposed adjacent each of said contact fingers in substantially parallelism therewith and engaging each of the, Opposite ends thereof for urging said contact fingers into high pressure engagement with said switch blade, tie bar means engaging a central portion of each of said leaf spring means for holding said portions in a fixed spacial relation, the frictional force generated between said switch blade and said contact fingers operating to pivot said contact fingers between first and second angular .positions when said switch blade ispivoted toward its open position, a cam surface formed on the pivotal end of each contact finger for engagementwith one of said bearing post means so that said pivotal ends are moved toward each other as said contact fingers pivot toward their second angular positions, whereby said leaf spring means are relaxed and said contact pressure is relieved, movement of said switch blade toward closed position being operative to pivot said contact fingers toward their first position whereby said contact pressure is re-established.

9. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means including a pair of opposed contact fingers having contact tip means near one end engageable by said switch blade when the latter is in its closed position, a bearing member having a pair of opposed bearing posts, each of said contact fingers being pivotally mounted near its other end on said bearing member and about a common axis that is substantially parallel to thepivotal axis of said switch blade, spring means engaging the outside of each of said contact fingers for urging them toward high pressure engagement with said switch blade, the frictional force generated between said switch blade and said contact fingers operating to pivot said contact fingers between first and second angular positions when said switch blade is pivoted toward its open position, a cam surface formed on the pivotal end of each contact finger for engagement with said bearing post means said cam surfaces each having a first depressed portion for engaging said bearing posts when said contact fingers are in their second position so that said pivotal ends are moved, toward each other as said contact fingers pivot toward their second angular positions whereby said contact pressure is relieved, said cam surfaces each having a second shallow portion for engaging said bearing posts when said contact fingers are in their first position so that movement of said switch blade toward closed position being operative to pivot said contact fingers toward their first angular position whereby said contact pressure is reestablished.

10. An electrical switch having a switch blade pivotally mounted for movement between open and closed positions, stationary contact means including a pair of opposed contact fingers having contact tip means near one end engageabile by saidswitch blade when the latter is in its closed position, a bearing member having a pair of opposed bearing posts, each of said contact fingers being pivotally mounted near its other end on said bearing member and about a common axis that is substantially parallel to the pivotal axis of said switch blade, spring means engaging the outside of each of said contact fingers for urging them toward high pressure engagement with said switch blade, the frictional force generated between said switch blade and said contact fingers operating to pivot said contact fingers between first and second angular positions when said-switch blade is pivoted toward its open position, a cam surface formed on the pivotal end of each contact finger for engagement with said bearing post means said cain surfaces each having a first depressed por. tion for engaging said bearing posts when said contact fingers are in their second position so that said pivotal ends are moved toward each other as said contact fingers pivot toward their second angular positions whereby said contact pressure is relieved, said cam surfaces each having a second shallow portion for engaging said bearing post-s when said contact fingers are in their first position so that movement of said Switchblade toward closed position being operative to pivot said contact fingers toward their first angular position whereby said contact pressure is reestablished, said cam surfaces each having a raised portion intermediate their ends so that a snap action is achieved as said contact fingers pivot between their first and second angular positions, the end of each of said cam surfaces being concave for abutment with said bearing posts so that the pivotal angle of said contact fingers is limited.

11. An electric switch having stationary contact means, a switch blade movable between connected and disconnected positions relative to said stationary contact means, a first means for providing contact pressure when said switch blade is in its connected position, and a second means operable as movement of said switch blade toward its disconnected position is initiated for relieving said contact pressure prior to the disengagement of said switch blade from said stationary contact means, said second means also being operative upon movement of said switch blade toward its connected position to re-establish said contact pressure after contact between said switch blades and said stationary contact means has been established.

1-2. An electric switch having a switch blade mounted for movement between open and closed positions, stationary contact means engageable by said switch blade when it is in its closed position and including opposed contact elements resiliently urged into high pressure engagement with said switch blade when the latter is in its closed position, and contact pressure relief means operative to relieve said contact pressure as'said switch blade moves toward its open position and prior to the disengagement of said switch blade from said stationary contact means, said contact pressure relief means also being operative upon movement of said switch blade toward its closed position to re-establish said contact pressure after contact between said switch blade and said stationary contact means has been re-established.

' References Cited in the file of this patent UNITED STATES PATENTS Wilkins July 3, 1934