US3500006A

US3500006A - Electric switch having improved electrically conducting hinge structure

Info

Publication number: US3500006A
Application number: US772715A
Authority: US
Inventors: Edmund W Kuhn
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-11-01
Filing date: 1968-11-01
Publication date: 1970-03-10
Anticipated expiration: 1987-03-10

Description

March 10, 1970 E. w. KUHN ELECTRIC SWITCH HAVING IMPROVED ELECTRICALLY CONDUCTING HINGE STRUCTURE 2 Sheets-Sheet 1 Filed Nov. 1. 1968 NW Q March 10, 1970 E. w. KUHN 3,500,006

- ELECTRIC SWITCH HAVING IMPROVED ELECTRICALLY CONDUCTING HINGE STRUCTURE 2 Sheets-Sheet 2 Filed Nov. 1, 1968 n h m m N M III E 8 a XE m m m I u mw S. m 4; R32 mm. n. 6 on B we 3. 87 N2 /VV\/\\\\\ 8. mm .2 8 S. 3. 3 N9 8 9: B. 8 mm. 2. mdE 2. ndE mM 9 8 l 8. on Q No- 8 2. cm 2. z.

ATTORNEY United States Patent U.S. Cl. 200-48 9 Claims ABSTRACT OF THE DISCLOSURE An electric switch comprising a switch blade movable between open and closed positions with respect to a relatively stationary contact means and supported by a hinge type conducting structure for rotational movement about its own axis and pivotal movement about an axis generally perpendicular to the switch blade.

BACKGROUND OF THE INVENTION This invention relates to electric switches and more particularly to hinge type electrically conducting structures which form part of such switches.

In certain types of outdoor, high voltage electric switches, a problem arises in providing a reliable electrical current path between certain relatively stationary parts of such switches and relatively movable parts, such as switch blades. This problem is aggravated where some electrically conducting parts of such a switch may be formed from aluminum to obtain certain advantages and other parts of the switch are formed from a different electrically conducting material, such as copper or a copper alloy. A construction of the latter type introduces the possibility of galvanic corrosion due to the presence of the dissimilar metals. Various constructions have been proposed in the past for switches of the type described,

SUMMARY OF THE INVENTION In accordance with the invention, an electric switch includes a switch blade or contact arm having one end movable into and out of engagement with an associated relatively stationary contact means. The switch blade has secured to the other end a generally tubular electrically conducting crank member which is rotatably supported on an electrically conducting hinge member having a generally tubular portion which projects axially into one end of the associated crank member. An electrically conducting shaft or rod is secured inside said crank member for movement therewith and includes a threaded portion which projects axially inside the tubular portion of the hinge member and engages an internally threaded portion of the hinge member to limit axial movement of the associated switch blade with respect to the hinge member. One or more resilient electrically conducting members is disposed between the tubular portion of the hinge mem ber and the associated shaft to maintain an electrically conducting path therebetween during all movements of the switch blade. The hinge member, in turn, may be pivotally supported for rotation about an axis which is generally perpendicular to the associated switch blade.

It is therefore an object of this invention to provide an electric switch including an improved electrically conducting hinge type structure.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a partial view, in side elevation, of a disconnecting switch structure embodying the principal features of the invention;

FIG. 2 is a top plan view of the switch structure shown in FIG. 1;

FIG. 3 is an enlarged top plan view, partly in section, of a portion of the switch structure shown in FIGS. 1 and ice FIG. 4 is an enlarged view, partly in side elevation and partly in section, of the portion of the switch structure shown in FIG. 3; and

FIG. 5 is an enlarged view, partly in end elevation and partly in section of a portion of the switch structure shown in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and FIGS. 1 and 2 in particular, there is shown a disconnecting switch assembly 10 which comprises three spaced

insulator stacks

32, 34 and 36 which'are normally mounted upon a common base support (not shown), as disclosed in detail in US. Patents 3,194,905 which was issued July 13, 1965 to F. W. Jewell et a1. and which is assigned to the same assignee as the present application. Each of the insulator stacks 32, 34 and 36 comprises a plurality of insulators which are preferably formed from porcelain or a similar insulating material. The number of insulators required in each of the

insulator stacks

32, 34 and 36 depends upon the voltage of the electrical system in which the disconnecting switch 10 is applied. As illustrated, the insulator stacks 32 and 34 may be mounted upon fixed pedestals or spacers (not shown) which, in turn, may be secured to the top of the associated base which may be a metal channel in configuration. As described in the last-mentioned patent, the insulator stack 36 is mounted upon a shaft (not shown) the lower end of which is rotatably mounted in a bearing (not shown) was is secured to the associated base. As indicated in FIG. 2, an operating lever or crank arm 37 may be secured to the shaft provided at the lower end of the insulator stack 36 to rotate the insulator stack 36 with the crank arm 37 being adapted for connection to any conventional means for operating the crank arm 37 to effect rotation of the associated shaft and the insulator stack 36 about its own longitudinal axis.

In order to positively connect the crank arm 37 and the associated rotatable insulator stack 36 to the balance of the operating mechanism of the disconnecting switch 10 as will be described hereinafter, a shaft 112 is secured to a flange member 113 which, in turn, is secured to the top of the insulator stack 36. The shaft 112 extends upwardly from the upper end of the insulator stack 36 to thus form an extension of the shaft which is provided at the lower end of the insulator stack 36.

The shaft 112 passes through an opening provided in the terminal end casting or member 110 which is substantially aligned with the axis of rotation of the shaft 112 and the associated insulator stack 36 and has mounted at the upper end thereof a crank arm which is rotatable with the shaft 112 and which extends generally at an angle or generally transversely with respect to the axis of rotation of the shaft 112. In order to facilitate the rotation of the shaft 112 inside the opening provided in the terminal end member 110, one or more sleeve bearings (not shown) may be disposed inside the opening provided in the terminal end member where desired.

It is to be noted that in a particular application, the crank arm 100 may be formed integrally with the shaft 112.

As illustrated in FIGS. 1 and 2, the disconnecting switch includes a generally U-shaped relatively stationary contact assembly or break jaw assembly 40 which is mounted on and secured to the top of the insulator stack 32. The stationary contact assembly 40 includes a plurality of pairs of spaced contact jaws 43 which are mounted on and interconnected by a generally U-shaped base member which is formed or cast from an electrically conducting material and which is secured to the top of the insulator stack 32 by suitable means, such as bolts. As illustrated, the contact jaws 43 may be secured to the associated base member or terminal casting 41 by suitable means, such as bolts, and may be biased toward one another by separate resilient means, such as springs (not shown). A terminal pad 42 which is adapted to receive a terminal connector may be formed integrally with or secured to one side of the base member or terminal casting 41. An upwardly extending member 44 may also be formed integrally with or secured to the other side of the base member or terminal casting 41 to act as a stop for the movement of the associated switch blade 50 into engagement with the contact jaws 43. Where desired, the base member or terminal casting 41 may be formed from aluminum and in such a construction, the contact jaws 43 are preferably formed from copper or an alloy of copper in order to avoid the problems associated with the high resistance oxide coating that would result if the contact jaws 43 were formed from aluminum and exposed to air. It is to be noted that the stationary contact assembly 40 is of the reverse loo-p type which has the characteristic of magnetically forcing the associated switch blade 50 downwardly between the break jaws 43 in a direction towards the base member 41 and against the blade stop 44 when relatively high momentary currents flow through the disconnecting switch 10.

Alternatively, the stationary contact assembly 40 may be constructed with the contact jaws 43 and the base member 41 formed as a unitary member from a suitable material which combines relatively high electrical conductivity with excellent spring characteristics, such as Zirconium copper or cadmium chrome copper, as described in detail in US. Patent 3,079,474 which issued Feb. 26, 1963, to E. F. Beach et al., and which is assigned to the same assignee as the present application. In such a construction, the resilient nature of the contact jaws substantially eliminates the need for additional Spring or biasing means to bias the contact jaws toward one another for gripping the free end of the associated blade 50 when the blade 50 is actuated to engage the stationary contact assembly 40.

In order to provide an electrically conducting path between the stationary contact assembly 40 and the electrically conducting parts of the disconnecting switch 10 which are mounted on top of the insulator stack 34 when the disconnecting switch 10 is in a closed circuit condition as shown in FIGS. 1 and 2, a movable switch blade 50 is provided. The blade 50 is elongated in shape and includes a main body or central portion 56 which is generally tubular in configuration and which is formed from an electrically conducting material such as copper, a copper alloy, or aluminum. The blade 50 also includes an end portion or beavertail member 53 at its left end which is generally rectangular in cross section to provide high pressure contact areas which are adapted to engage the contact jaws 43 of the stationary contact assembly 40. The end portion 53 of the blade 50 may be formed integrally with the associated main body portion 56 or may be formed as a separate piece which is secured to the left end of the main body portion 56 by suitable means, such as welding, as indicated at 55 for movement with the main body portion 56. If the main body portlon 56 of the blade 50 is formed from copper or a copper alloy, the end portion 53 may be conveniently formed integrally with the main body portion 56 by flattening the left end of the switch blade 50 to form high pressure contact areas on the sides of the end portion 53 which are adapted to directly engage the contact jaws 43 of the stationary contact assembly 40.

On the other hand, if the main body portion 56 of the blade 50 is formed from aluminum, the end portion 53 may be conveniently formed as a separate member which projects axially into the left end of the main body portion 56 and is secured to the left end of the main body portion 56 by suitable means, such as welding. Where the main body portion 56 and the end portion 53 of the blade 50 are both formed from aluminum, one or more contact members formed from copper or a copper alloy is preferably secured to the end portion 53 by suitable means, such as bolts, for movement therewith. The separate contact members 51 secured to the end portion 53 in such a construction are necessary in order to avoid the problems which would otherwise result if the end portion 53 were simply formed from aluminum and the contact areas on the end portion of the switch blade 50 were subject to the formation of a high resistance oxide coating when exposed to atmospheric conditions.

When the disconnecting switch 10 is to be applied at high transmission voltages, a corona shielding member 46 may be mounted at the left end of the end portion 53 of the switch blade 50. More specifically, the corona shielding member 46 may be generally hollow spherical in configuration and include a threaded portion which is adapted to screw into an internally threaded opening provided at the left end of the end portion 53 of'the switch blade 50 with the corona shielding member 46 being formed from an electrically conducting material, such as aluminum.

In order to support the switch blade 50 for rotation about its own axis and for arcuate movement about an axis which extends generally transversely with respect to the axis of the blade 50, the right end of the main body portion 56 of the blade 50- is secured to the left end of a generally tubular crank member 60 for movement therewith. More specifically as illustrated in FIG. 4, the left portion of the crank member 60, as indicated at 61, projects axially into the right end of the main body portion 56 of the blade 50 and the left portion 61 of the crank member 50 is secured to the right end of the main body portion 56 of the blade 50 by suitable means, such as welding or brazing, as indicated at 62 in FIGS. 3 and 4. Where the main body portion 56 of the switch blade 50 is formed from copper or a copper alloy, the crank member 60 is also preferably formed from a copper or copper alloy material in order to avoid galvanic corrosion at the joint between the main body portion 56 of the blade 50 and the crank member 60. Similarly, where the main body portion 56 of the blade 50 is formed from aluminum, the crank member 60 is also preferably formed from aluminum to avoid the problem of galvanic corrosion at the joint between the respective parts.

In order to support the crank member 60 and, in turn, the switch blade 50 for rotation about a common axis which extends longitudinally of the switch blade 50, the hinge member 70 includes a generally tubular portion 79, as shown in FIG. 4, which projects axially inside the enlarged right-hand portion of the crank member 60 with the tubular portion 79 of the hinge member 70 being disposed in telescoping relation with the enlarged righthand portion 62 of the crank member 60. In order to facilitate the rotation of the crank member 60 on the tubular portion 79 of the hinge member 70, a band 168 of bearing material having a low coefficient of friction, such as polytetrafiuoroethylene which is sold under the trademark Teflon, may be disposed on the outer surface of the tubular portion 79 of the hinge member 70 adjacent to a shoulder which is provided on said tubular portion between the right end of the crank member 60 and the tubular portion 79 of the hinge member 70*. In order to seal off the space inside the crank member 60 at the right end of the crank member 60 and to substantially prevent the entrance of moisture inside the crank member 60 which might cause galvanic corrosion between certain electrically conducting parts which will be described hereinafter, a sealing member of the O-ring type, as indicated at 166, is disposed between the right end of the crank member 60 and the outer surface of the tubular portion 79 of the hinge member 70 and is retained in position by an associated recess provided in the tubular portion 79 of the hinge member 70. It is to be noted that the hinge member 70 is preferably formed from copper or a copper alloy for reasons which will be explained hereinafter.

In order to provide an electrically conducting path between the blade 50 and the associated crank member 60 and the hinge member 70 and to substantially prevent axial movement of the blade 50 and the associated crank member 60 with respect to the hinge member 70 while still permitting limited rotary movement of the blade 50 and the associated crank member 60 with respect to the tubular portion 79 of the hinge member 70, the electrically conducting elongated shaft or rod 150 is secured to the crank member 60 inside the crank member 60 and projects axially into the tubular portion 79 of the hinge member 70, as best shown in FIG. 4. The left end of the shaft 150 is externally threaded as indicated at 152 to engage an internally threaded portion 63 of the crank member 60. In addition, the shaft 150 includes an intermediate tapered portion 154 which is adapted to bear against an internal portion 64 of the crank member 60 having substantially the same shape. It is to be noted that the left end of the shaft 150 includes an internally threaded opening, as indicated at 153, and is slotted, as indicated at 151, to permit radial expansion by insertion of a threaded pipe plug 134. It is also to be noted that the shaft 150 is preferably formed from an electrically conducting material other than aluminum, such as tin plated copper or a copper alloy, in order to avoid certain problems which might otherwise result, such as galvanic corrosion or other problems associated with the use of dissimilar metals in the relatively movable electrically conducting parts of the shaft 150 and the hinge member 70.

The shaft 150 is necessarily assembled with the associated crank member 60 prior to the welding or securing of the crank member 60 of the switch blade 50. In the assembly of the shaft 150 inside the crank member 60, the threaded portion 152 of the shaft 150 is first screwed into position inside the threaded portion 63 of the crank member 60. Where the crank member 60 is formed from aluminum and the shaft 150 is formed from tin plated copper, the threaded portion 63 of the crank member 60 should have a petroleum base joint compound applied thereto prior to the assembly of the threaded portion 152 on the shaft 150 inside the threaded portion 63 of the crank member 60 to prevent oxidation of the threaded portion of the aluminum crank member when the parts are assembled in a joint structure. Next, the pipe plug 134 should be screwed into the internally threaded opening 153 at the left end of the shaft 150 to radially expand the slotted end of the shaft 150 to thereby insure adequate contact pressure between the threaded portion 152 of the shaft 150 and the internally threaded portion 63 of the crank member 60. When the pipe plug 134 is tightened into the opening at the left end of the shaft 150 as just mentioned, the tapered portion 154 of the shaft 150 will also be forced into a relatively high pressure engagement with the tapered inner surface 64 of the crank member 60 which is engaged by the tapered portion 154 of the shaft 150. When the shaft 150 is assembled with the crank member 60 as just described, an electrically conducting path or joint is established between the crank member '60 and the shaft which is capable of carrying relatively high momentary current, such as 100,000 amperes or more. Finally, in order to close off the opening inside the crank member 60 to the left of the pipe plug 134, as viewed in FIG. 4, and to substantially seal olf said opening, an additional plug 132 may be assembled in a friction fit inside the crank member 60, as shown in FIG. 4. Where the crank member 60 is formed from aluminum, the plug 132 should also be formed from aluminum to avoid problems due to galvanic corrosion.

After the shaft 150 is assembled with the crank member #60 in the manner just described, the crank member 60 may then be secured to the associated blade 50 y welding, as indicated at 62, or by some other suitable method. It is to be noted that after the shaft 150 is assembled with the crank member 60, a hole may be drilled transversely into the crank member 60, the shaft 150 and the pipe plug 134 and a spring pin, as indicated at 136, may be assembled into the hole and retained therein by a friction fit to prevent rotation of the pipe plug 134 and the shaft 150 in place after assembly with the associated crank member 60.

In order to retain the blade 50 and the associated crank member 60 in assembled relation with the associated tubular portion 79 of the hinge member 70 and more specifically to substantially prevent axial movement of the switch blade 50 and the crank member 60 with respect to the hinge member 70, while permitting limited rotation of the crank member 60 and the switch blade 50 with respect to the tubular portion 79 of the hinge member 70, the right end of the shaft 150 is threaded, as indicated at 158. As shown in FIG. 4, the threaded portion 158 of the shaft 150 at the right end of said shaft is assembled into threaded engagement with an internally threaded portion 75 of the tubular portion 79 of the hinge member 70. In order to facilitate the rotation of the shaft 150 with respect to the tubular portion 79 of the hinge member 70, a band 167 or coating of material having a low coefiicient of friction, such as polytetrafluoroethylene, previously mentioned, may be disposed on the outer surface of the central portion 156 of the shaft 150 between the left end of the tubular portion 79 of the hinge member 70 and the enlarged central portion of the shaft 150, as indicated at 156. It is to be noted that the engagement of the threaded portion 158 with the threaded portion '75 of the hinge member 70 establishes an electrically conducting path between the shaft 150 and the hinge member 70 having additional current carrying capacity.

In order to establish a relatively high capacity current carrying path between the shaft 150 and the tubular portion 79 of the hinge member 70, one or more resilient electrically conducting members, as indicated at 162 and 164, is disposed in the annular space between the tubular portion 79 of the hinge member 70 and the intermediate portion 157 of the shaft 150. More specifically, each of the resilient conducting

members

162 and 164 may comprise a resilient corrugated, sheet metal, electrically conducting sleeve which includes a plurality of ridges, as shown in FIG. 5, which alternately engage the tubular portion 79 of the hinge member 70 and the shaft 150. As described in detail in Us. Patent 3,201,535 which was issued Aug. 1'7, 1965 to V. F. Sabol et al, and which is assigned to the same assignee as the present application, each of the

electrically conducting members

162 and 164 is split providing two end portions that are biased apart by means of a wedge member 169 so that the ridges thereof will be biased against the tubular portion 79 and the shaft 150.

The electrically conducting

members

162 and 164 are preferably formed from a material which combines relatively high electrical conductivity with excellent spring or resilient characteristics, such as phosphorus-bronze or a zirconium-copper alloy. Where desired, the electrically conducting

members

162 and 164 may be axially spaced from one another by a suitable spacer, as indicated at 163. It is important to note that the electrically conducting path which is formed between the tubular portion 79 of the hinge member 70 and the shaft 150 avoids the problems of galvanic corrosion since the shaft 150 as preferably formed from a tin plated copper or copper alloy material and the tubular portion of the hinge member 70 is also formed from a copper or copper alloy material. It it also to be noted that the electrically connecting path which is provided between the tubular portion 79 and the shaft 150 is maintained in all operating positions of the crank member 60 during any rotary movement of the crank member '60 and the associated blade 50 with respect to the hinge member 70. Any space which remains inside the crank member 60 between the tubular portion 79 of the hinge member 70 and the crank member 60 may be filled with a suitable grease, such as silicone grease, to cooperate with the sealing member 166 to substantially prevent the entrance of moisture which might otherwise promote oxidation or galvanic corrosion between the different parts of the assembly which are formed from either aluminum or copper or a copper alloy. Finally, it is to be noted that the electrically conducting path between the crank member 60, the shaft 150 and the tubular portion 79 of the hinge member 70 is completely enclosed and substantially sealed to protect the current carrying paths provided from the effects of atmospheric conditions and the oxidation or galvanic corrosion that might otherwise result in such a structure due to the presence of different electrically conducting materials, such as copper and aluminum.

In the assembly of the blade 50 and the crank member 60 with the tubular portion of the hinge member 70, the shaft 150 is first assembled with the crank member 60 as previously described. Next, the crank member 60 is secured to the blade 50 by suitable means such as welding. The blade 50 and the associated crank member 60 are then assembled with the hinge member 70 and the threaded portion 158 of the shaft 150 is screwed into engagement with the internally threaded portion 75 of the tubular portion 79 of the hinge member 70 with the

electrically conducting members

162 and 164 in position, as shown in FIG. 4.

In order to support the hinge member 70 for rotation about an axis which is generally transverse or perpendicular with respect to the axis of the blade 50 and to support the blade '50 which is assembled on the hinge member 70 for arcuate movement or travel about said axis, the spaced arms 82 of the hinge support member 80 are disposed on opposite sides of the hinge member 70, as best shown in FIG. 3. As shown in FIG. 3, the hinge member 70 includes a pair of

hinge portions

78A and 78B which project in opposite directions and are disposed generally perpendicular to the axis of the tubular portion 79 of the hinge member 70. The hinge member 70 is pivotally supported between the arms 82 of the hinge support frame 80 by the electrically conducting hinge pins or studs 72 Which pass through substantially aligned openings provided in the arms 82 and the

hinge portions

78A and 78B of the hinge member 70. The heads of the hinge pins 72 are removably secured to the arms 82 of the support frame 80 by suitable means, such as a plurallty of bolts -or screws 71, which pass through substantially aligned openings in the hinge pins 72 to engage the internally threaded openings in the arms 82 of the support frame 80. The hinge pins 72 are preferably formed from copper or a copper alloy. The openings in the

hinge portions

78A and 78B are partially enlarged and adapted to receive the electrically conducting members 76 which are disposed in the annular spaces between the h1nge pins 72 and the inner surfaces of the openings 1n the

hinge portions

78A and 78B. The electrically conducting members 76 are provided to establish electrically conducting paths between the hinge member 70 and the hinge pin 72 and have the same construction and are formed from the same electrically conducting materials previously described in connection with the

electrically conducting members

162 and 164. In order to seal off the ends of the openings in the

hinge portions

78A and 78B to thereby substantially prevent the entrance of moisture or other contaminating materials, the sealing members 75 which may be of the O-ring type are disposed between the hinge pins 72 and the

hinge portions

78A and 78B and are retained in position by the recesses provided in the hinge pin 72, as best shown in FIG. 3. The hinge support member or frame 8 is formed from an electrically conducting material such as aluminum, copper or a copper alloy. Where the hinge support member 80 is formed from aluminum, a suitable grease type petroleum base joint compound may be provided as part of the bolted joints between the hinge pins 72 and the arms 82 of the hinge support member 80. Where the hinge support member is formed from copper or copper alloy, the hinge pins 72 may be externally threaded adjacent to the heads of said hinge pins to engage internally threaded openings in the arms 82 of the hinge support member 80 to secure said hinge pins to the arms 82 of the hinge support member 80.

In order to provide an electrically conducting path between the hinge support member 80' and the terminal end casting or member 110 which is mounted on top of the rotatable insulator stack 36, the generally tubular, electrically conducting member 86 structurally connects the hinge support member 80 and the terminal end member 110. More specifically, the hinge support member 80 includes a flange portion 84 having an opening therein which is adapted to receive the left end of the electrically conducting member 86 as best shown in FIG. 1 with the left end of the electrically conducting member 86 being secured to the flange portion 84 by suitable means, such as welding. Similarly, the terminal end member 110- also includes a flange portion 114 having an opening therein which is adapted to receive the other end of the electrically conducting member 86 with the right end of the electrically conducting member being secured to the flange portion 114 by suitable means, such as welding. The conducting member 86 may be for-med from a suitable electrically conducting material such as copper, a copper alloy or aluminum. Where the hinge support member 80 is formed from aluminum, the electrically conducting member 86 is also preferably formed from aluminum along with the terminal end member 110 being preferably formed from aluminum to avoid the problems associated with galvanic corrosion at the joints between the electrically conducting member 86 and the hinge member 80 and the terminal end member 110 at the opposite ends of the conducting member 86. The conducting member 86 may also serve as a housing for a counter-balancing mechanism or means which is described in detail in U.S. Patent 3,079,474 which issued Feb. 26, 1963, to E. F. Bech et al. and which is assigned to the same assignee as the present application. As indicated in FIG. 3, the counterbalancing mechanism which may be disposed in the electrically conducting member 86 may be operatively connected to the 'hinge member 70 by the link 83 shown in FIG. 3 which may be pivotally connected to the hinge member 70 by the pivot pin which passes through substantially aligned openings in the link 83 and the hinge member 70, as shown in FIG. 3.

When the disconnecting switch 10 is in the closed circuit condition shown in FIGS. 1 and 2, an electrically conducting path extends from the terminal pad 42 at the left end of the disconnecting switch 10 to the terminal pad 116 at the right end of the disconnecting switch 10 through the base member 41 and the contact jaws 43 of the stationary contact assembly 40, one or more contact members 51 on the end portions 53 of the switch blade 50, the end portion 53, the main body portion 56 of the blade 50, the crank member 60, the elongated shaft 50, the electrically conducting

members

162 and 164,

the hinge member 70, the electrically conducting members 76, the electrically conducting hinge pins 72, the hinge support member 80, the electrically conducting member 86 and the terminal end member 110 to the terminal pad 116. An electrically conducting path also extends from the shaft 150 to the hinge member 70 through the threaded portion 158 of the shaft 150 to the internally threaded portion 75 of the hinge member 70 which is electrically in parallel with the electrically conducting path provided between the shaft 150 and the hinge member 70 through the electrically conducting

members

162 and 164.

In order to operatively connect or mechanically couple the crank arm 100, which is mounted on or formed integrally with the shaft 112 which is secured to the top of the rotatable insulator stack 36, and the crank member 60 in order to permit the movement of the switch blade 50 during opening and closing operations of the disconnecting switch 10, the disconnecting switch includes the operating link 90 which is pivotally connected to the crank member 60, the slip joint 92 and the universal joint 120 which operatively connects the slip joint 92 to the crank arm 100.

More specifically, the crank arm 100 includes a clevis portion which comprises the spaced arms 101 at the upper end thereof, as best shown in FIG. 1. As just mentioned, the crank arm 100 is operatively connected to the operating link 90 by the universal joint structure 120 and the slip joint structure 92. The universal joint structure 120 comprises a trunnion member 102 which is pivotally supported in substantially aligned openings provided in the spaced arms 101 of the crank ar-m 100 by a pair of pivot pins 102 which are secured to the trunnion member 102 for movement therewith. The universal joint structure 120 additionally includes a clevis member 93 which is pivotally connected to the trunnion member 102 by the pivot pin 104 for rotation about an axis which is generally perpendicular to the other axis of rotation of the trunnion member 102. The clevis member 93 includes a partially threaded extension which passes into a bore provided in the right end of the operating link 90 and has disposed thereon an adjusting nut 99 which forms part of the slip joint structure 92 as described in detail in US. Patent No. 3,194,905, previously mentioned. As disclosed in detail in the US. patent just mentioned, the slip joint 92 permits limited relative movement between the operating link 90 and the clevis member 93 and includes a spring (not shown) which prevents bouncing of the switch blade 50 during a closing operation.

The operating link 90 which is of the forked type is pivotally connected to the crank portion 66 of the crank member 60 by the pivot pin 67 which passes through an opening 68 provided in the crank portion 66 of the crank member 60.

In the operation of the disconnecting switch 10 as described in greater detail in the last mentioned patent, it is assumed that the blade 50 is in the closed position, as shown in FIGS. 1 and 2, with the movable contact members 51 in engagement with the contact jaws 43 of the stationary contact assembly 40 and the end portion 53 of the blade 50 in engagement with the blade stop 44. Under these conditions, the operating mechanism of the disconnecting switch 10 which includes the operating link 90, the slip joint structure 92, the universal joint structure 120 and the crank arm 100 considered as an overall toggle mechanism is in an overtoggle position, as best shown in FIG. 2.

During an opening operation of the disconnecting switch 10 when the crank arm 100 is rotated in a counterclockwise direction as viewed in FIG. 2, the toggle mechanism of the disconnecting switch 10 as just described moves through a dead center position to an undertoggle position to effect opening of the disconnecting switch 10 to thereby actuate the blade 50 from the closed position shown in FIG. 1 to the open position in which the blade 50 is angularly displaced from the closed position by approximately in a clockwise direction about the axis defined by the hinge pins 72. During an opening operation of the disconnecting switch 10, the slip joint structure 92 effectively shortens the length of the operating link 90 as the crank arm starts to rotate in a counterclockwise direction about its own axis of rotation to permit the toggle mechanism which includes the operating link 90 and the crank arm 100 to pass through the dead center position. As the crank arm 100 rotates further toward the undertoggle position from the dead center position, the slip joint 92 effectively lengthens the operating link 90 to thereby eliminate any longitudinal pull on the operating link 90 but to transmit a force from the crank arm 100 to the operating link 90 through the clevis member 93 which provides a lateral force on the crank member 60 to rotate the blade 50 about its own axis to effect a disengagement of the blade 50 from the contact jaws 43 of the stationary contact assembly 40. Continued counterclockwise movement of the crank arm 100 provides a longitudinal pull on the operating link 90 since the lengthening of the operating link 90 is limited by the slip joint structure 92 and a force is therefore transmitted to the crank member 60 to actuate movement of the switch blade 50' along with the hinge member 70 in a counterclockwise direction about the axis defined by the hinge pins 72 until the blade 50 is in a substantially vertical position, as viewed in FIG. '1.

During a closing operation of the disconnecting switch 10, the crank arm 100 is actuated or moved in a clockwise direction from the undertoggle position which corresponds to the open position of the disconnecting switch 10. During a closing operation of the disconnecting switch 10, when the crank arm 100 is moved in a clockwise direction from the undertoggle position, the blade 50 is rotated in a counterclockwise direction from the open position until the blade 50 and, more specifically, the left end of the blade 50 is actuated to a position between the contact jaws 43 and the end portion 53 of the blade 50 rests upon the blade stop 44. Further rotation of the crank arm 100 effects movement of the toggle linkage which includes the operating link 90 and the crank arm 100 through the dead center position and to the overtoggle position to thereby extend the slip joint structure 92 and to rotate the left end of the blade 50 into full engagement with the fixed contact jaws 43 of the stationary contact assembly 40 while the blade itself rests on the blade stop 44. In summary, the operating mechanism of the disconnecting switch 10 separates the rotary movement of the blade 50 about its own axis which is necessary to either disengage or cause the left end of the blade 50 to fully engage the stationary contact assembly 40 and the generally arcuate movement of the blade 50 between the open and closed positions just described.

It is important to note that the construction of the disconnecting switch 10 permits the transmission of mechanical forces between the blade 50 and the associated crank member 60 and the crank arm 100 while providing a relatively high capacity electrically conducting path between the blade 50 and the associated hinge member 70 to thereby assure the reliable operation of the disconnecting switch 10 when exposed to outdoor atmospheric conditions over extended periods of service.

It is to be understood that the teachings of the invention may be applied to a disconnecting switch structure in which substantially all of the current carrying parts are formed from copper or a copper alloy or, alternatively, most of the important electrically conducting parts may be formed from aluminum, such as the base member 41 of the terminal end member at the left end of the disconnecting switch 10, the end portion 53 of the blade 50, the main body portion 56 of the blade 50, the crank member 60, the hinge support member 80, the electrically conducting member 86, and the terminal end member 110, while the balance of the electrically conducting parts in such a dual metal construction are preferably formed from copper or a copper alloy, such as the contact jaws 43, one or more contact members 51 on the left end of the blade 50, the elongated shaft 150, the electrically conducting

members

162 and 164, the hinge member 70, the hinge pins 72 and the electrically conducting members 76 which are all involved in relatively movable current carrying parts which may be called upon to conduct relatively high momentary currents such as 100,000 amperes or more.

The apparatus embodying the teachings of this invention has several advantages. For example, an electrically conductive path is provided between a movable switch blade and the associated hinge supporting parts which is protected from adverse atmospheric conditions which might otherwise cause corrosion problems or high resistance in the current carrying joints. In addition, the disclosed disconnecting switch construction readily lends itself to the use of aluminum parts which may be combined with electrically conducting parts formed from copper or copper alloys in a dual metal construction. In other words, a disconnecting switch construction as disclosed permits the use of aluminum in many of the current carrying parts to thus reduce the weight of the overall disconnecting switch and to reduce the load which must be carried by the supporting insulator stacks such as the insulator stacks 32, 34 and 36. Finally, the disconnecting switch construction including both aluminum conducting parts and electrically conducting parts formed from copper or copper alloy substantially prevents the occurrence of galvanic corrosion or oxidation which would otherwise cause a gradual reduction in the ability of the various electrically conducting parts to carry current when a disconnecting switch is employed over long periods of time in an electrical system.

Since numerous changes may be made in the above described apparatus and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An electric switch comprising a. relatively stationary contact member, an elongated switch blade having one end movable between engaged and disengaged positions with respect to said stationary contact member, a generally tubular, electrically conducting crank member secured to the other end of said blade for movement therewith, an electrically conducting hinge member having a generally tubular portion projecting axially into one end of said crank member to support said blade for rotation about its own axis, an electrically conducting shaft having one end secured to said crank member inside said crank member for movement therewith, the other end of said shaft projecting axially inside the tubular portion of said hinge member, resilient, electrically conducting means disposed between and to bear against both said other end of sa d shaft and said tubular portion of said hinge member to maintain an electrically conducting path therebetween, and a hinge support member disposed to pivotally support said hinge member for rotation about an axis which is generally perpendicular to said blade.

2. The combination as claimed in claim 1 wherein said other end of said shaft includes a threaded portion which engages an internally threaded portion of said tubular portion of said hinge member to limit axial movement of said blade with respect to said hinge member.

3. The combination as claimed in claim 1 wherein said blade includes a main body portion which is formed from aluminum, said crank member is formed from aluminum, and said shaft and hinge member are both formed from an electrically conducting material which is at least partially copper.

4. The combination as claimed in claim 1 wherein sealing means is disposed between said one end of said crank member and said tubular portion of said hinge member.

5. The combination as claimed in claim 1 wherein the other end of said blade is generally tubular and the other end of said crank member projects axially inside the other end of said blade with said crank member being welded to said blade adjacent to the other end of said crank member.

6. The combination as claimed in claim 1 wherein said crank member includes an inner surface which is tapered from a relatively larger size to a relatively smaller size and said shaft includes a tapered portion having a shape similar to that of said inner surface and which engages said inner surface.

7. The combination as claimed in claim 2 wherein said blade includes a main body portion which is formed f om aluminum, said crank member is formed from aluminum and said shaft and hinge member are both formed from an electrically conducting material which is at least partially copper.

8. The combination as claimed in claim 2 wherein sealing means is disposed between said one end of said crank member and said tubular portion of said hinge member.

9. The combination as claimed in claim 2 wherein the other end of said blade is generally tubular and the other end of said crank member projects axially inside the other end of said blade with said crank being welded to said blade adjacent to the other end of said crank member.

References Cited UNITED STATES PATENTS 2,658,964 11/ 1953 Heberlein. 2,673,903 3/ 1954 Heberlein. 3,038,052 6/ 1962 Froland.

ROBERT K. SCHAEFER, Primary Examiner H. J. HOHAUSER, Assistant Examiner