US3917920A

US3917920A - Manually operated rotary switch and combination load contact-fuse clip therefor

Info

Publication number: US3917920A
Application number: US481055A
Authority: US
Inventors: Ronald G Pekrul; Louis T Stegmaier; Joseph J Mrowka
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1973-08-20
Filing date: 1974-06-20
Publication date: 1975-11-04
Anticipated expiration: 1992-11-04

Abstract

A double-break rotary electrical switch includes an insulative housing having interior walls defining isolated switching chambers and serving to journal a rotor mounting a plurality of switching blades. A plurality of integral conductive straps of Sshaped configuration each includes a contact portion engageably with a different one of the switching blades and a fuse clip portion defining a slot for receiving a fuse terminal. Each strap is mounted by bolts to the underside of a horizontal support plate affixed to the housing and spanning each of the switching chambers. The strap mounting bolts also maintain a conductive insert positioned in each fuse clip slot to adapt the clip for acceptance of smaller sized fuse terminals. Each support plate is notched to expose the fuse clip portion thereunder for acceptance of a fuse terminal.

Description

United States Patent 1 1 Pekrul et a1.

[ Nov. 4, 1975 General Electric Company, New York, NY.

[22] Filed: June 20, 1974 [21] Appl. No.: 481,055

Related US. Application Data [62] Division of Ser. No 389,979, Aug 20, |973, Pat. No.

[73] Assignee:

[52] US. Cl.. 200/162; 200/254; 200/284; 337/209; 339/252 F; 339/258 F [51] Int. Cl. ..H0lH l/42;H01H 21/54; HOIH 85/22;H01R 11/22 [58] Field of Search 200/11 R, 14, 15, 155 R,

200/162, 237, 252, 254, 255, 256, 273, 274, 280, 282, 284; 337/9, 10, 208-215; 339/252 F, 253 F, 256 C, 258 F, 259 F, 262 F 3.287.533 11/1966 Rys .1 200/162 3,525,838 8/1970 Ruseriko 200/162 X 3,575,566 4/1971 Rys 200/162 3,588,413 6/1971 Stanback...1 .1339/258 F X 3,632,935 1/1972 Stegmaier .1 200/254 X 3,840,717 10/1974 Pekrul et a1. .1 200/284 FOREIGN PATENTS OR APPLICATIONS 1,110,012 4/1968 United Kingdom 339/258 F 945,269 7/1956 Germany .1 200/256 Primary Examiner-James R. Scott Attorney, Agent, or Firm R. A. Cahill; W. C. Bernkopf; F. L. Neuhauser 57] ABSTRACT A double-break rotary electrical switch includes an insulative housing having interior walls defining isolated switching chambers and serving to journal a rotor mounting a plurality of switching blades. A plurality of integral conductive straps of S-shaped configuration each includes a contact portion engageably with a different one of the switching blades and a fuse clip portion defining a slot for receiving a fuse termi nal. Each strap is mounted by bolts to the underside of a horizontal support plate affixed to the housing and spanning each of the switching chambers. The strap mounting bolts also maintain a conductive insert positioned in each fuse clip slot to adapt the clip for acceptance of smaller sized fuse terminals. Each support plate is notched to expose the fuse clip portion there under for acceptance of a fuse terminal.

2 Claims, 6 Drawing Figures US. Patent Nov. 4, 1975 Sheet 1 of 2 MANUALLY OPERATED ROTARY SWITCH AND COMBINATION LOAD CONTACT-FUSE CLIP THEREFOR This is a division of application Ser. No. 389,979, filed Aug. 20, 1973, now US. Pat. No. 3,840,717.

This invention relates generally to electric switches of heavy duty ratings and is particularly applicable to manually operated rotary switches having low profile housings and to a new and improved combination load contactfuse clip unit which is economical to manufacture and is suited for use in such switches having a wide range of ratings and variations.

Manually operated fused enclosed electric switches having ratings of the order of up to 100 a., 240 v. or more have heretofore, commonly employed a handle operated rotary switch in series with a fuse in each of the phases of the protected electrical circuit. Typically, the load contact in such a switch is selectively engaged and disengaged by a movable blade of the rotary switch for closing and opening the switch and is cantilever supported in spaced parallel relation with the movable blade by an upstanding interior wall of the molded insulated housing of the switch. The fuse clip for receiving one end of the associated fuse for such a load contact has commonly been positioned above the load contact to project in the opposite direction from the load contact and has been clamped to the load contact by suitable fasteners. Since the area of effective contact between the load contact and the fuse clip does not extend to the full cross-section of the joint therebetween, heat was generated by the heavy currents passing through the joint. Moreover, the projection of the load contact and the fuse clip in opposite directions has required a housing sufficiently deep to accommodate combined heights of these assembled parts.

It is an object of the present invention to provide a unique load contact-fuse clip unit which is economical to manufacture and is efficient and durable in use.

Another object of this invention is to provide a new and improved combination load contact-fuse clip which can be fabricated by simple bending and punching operations and which minimizes the quantity of copper required therefor.

A further object of this invention is to provide a new and improved combination load contact-fuse clip unit which is provided with an improved alignment and support arrangement.

Still another object of this invention is to provide a fused manually operated rotary switch incorporating a combination fuse clip-load contact unit which accommodates a low profile switch housing.

Still another object of this invention is to provide a manually operated double break rotary switch having a combination load contact-fuse clip unit mechanically supported in the switch housing by a support member which spans the unit for improved mechanical support and alignment accuracy.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

A better understanding of the invention will be obtained from the following detailed description and the accompanying drawing of an illustrative application of the invention. In the drawings:

FIG. 1 is a side view, partly broken away, of a fused manually operated double break rotary switch incorporating the present invention;

FIG. 2 is a framentary top view of the switch mechanism of FIG. 1;

FIG. 3 is a cross-sectional view taken along the lines 3-3 of FIG. 1;

FIG. 4 is a side view of the load contact-fuse clip of the present invention;

FIG. 5 is an end view of a variant form of the combination load contact-fuse clip unit of the present invention, and

FIG. 6 illustrates another variation of the present invention.

To describe the invention in further detail, there is shown in FIG. 1, a heavy duty fused manually operated double break rotary electrical switch which is housed in an insulating enclosure 10 which journals a rotor 12 in the end wall thereof. The rotor 12 is provided with a square extension 13 through one of the end walls for connection to a handle, not shown, for the manual operation of the rotor.

The rotor 12 mounts a plurality of switches 14 having switch blades 15 for rotation therewith. As shown, switch blades 15 comprise a pair of parallel blades l6, l8 engageable with the load and line contacts 20, 22 (FIG. 3) to fonn a double break switching arrangement for opening and closing the switch.

The switch 14 of only one of the phases of the protected line is fully illustrated. However, identical switches such as switch 14a, are positioned axially along the rotor 12 for each phase of the protected circult.

Associated with each of the

contacts

20, 22 are are

enclosures

26, 28, respectively, which serve to shield the arc generated between the blades of the switch 14 and the

contacts

20, 22, respectively, as the switch is being opened, it being understood that the flexure of the blades 16, 18 against the bias of springs 17 causes the blades to resiliently grip the

contacts

20, 22 when the switch is closed. A fuse (shown in phantom) having a blade is shown as being connected in series with the rotary switch 14. The blade 30 of the fuse is resiliently received in the receiving slot 36 of the spaced parallel

upstanding legs

32, 34 as best shown in FIG. 1.

As shown in FIG. 4, the leg 34 is bifurcated so that each of the bifurcated portions 34a, 34b is resiliently biased into engagement with the blade 30 of the fuse independently of the other. This coupled with the upset dimples 70 assure contact between the blade 30 and the fuse clip despite any misalignment of the blade 30 and the receiving slot 36 of the fuse clip. Projections 38 retain the fuse blade within the slot under short circuit conditions. It will be noted that each of the bifurcated portions 34a, 34b of the leg 34 are directly backed by the leg 32 of the fuse clip so that the blade 30 is clamped directly therebetween. Flat reinforcing springs span the closed end of the fuse clip and projections 40 of the spring are received in notches 42 provided in backing leg 32 to fix each reinforcing spring 35 in assembled position to reinforce and bias each of the bifurcations 34a, 34b toward the backing wall provided by leg 32. The springs 35 are formed of a spring steel having a high yield strength and elongation to reinforce and bias the

legs

32, 34 of the fuse clip into good electrical contact with the fuse blade 30 throughout the life of the switch despite any fatigue which may take place in the copper forming the fuse clip during use.

As will be apparent from the drawings, the combination fuse clip load contact is formed from a unitary strip of copper by being bent into a generally S-shape configuration by a simple bending operation and the shape and upset portions of the combination unit may be produced in a simple punch press operation. As a result, a load contact fuse clip construction formed from a single piece of stock having the maximum current carrying capacity can be produced economically.

Referring particularly to FIGS. 1 and 2, the combination load contact-fuse clip unit is provided with a support member 44 which is formed separately therefrom and is connected to the combination load contact-fuse clip by fastening screws 46 engaging horizontal wall 45 formed intermediate the fuse clip and load contact portions thereof. The support member 44 spans, or extends laterally beyond the load contact and fuse clip in both directions and is secured by fasteners 48, 50, respectively, to upstanding walls 54, 56 which define a switching chamber isolated from like switching chambers for the switches of the other phases. Not only does this construction provide high accuracy of alignment of the load contact and fuse clip with the housing and the rotor blades of rotor 14, due to the distance between the points of support provided by the screws 48 and 50, but also this construction causes less mechanical stresses to be imposed on the housing as a result of the sudden opening of the switch or the replacement of the fuse. As best shown in FIG. 2, a comer of support member is cut away at 52 to expose the receiving slot 36 between the legs of the fuse clip to accommodate the downward insertion of the blade 30 of a cartridge fuse. A pair of apertures in the support member receive the upstanding locators 53 molded in the enclosure for additional alignment accuracy.

As shown in FIG. 1, the fuse clip and load contact are disposed on one side of support member 44 and at the same horizontal level so that the housing may have a low profile as compared with a heretofore commonly used design in which the fuse clip was disposed directly above the load contact.

Since in the design of the present invention, the wall 58 which serves the function of isolating the arc produced by opening the switch for one phase from the switch for an adjacent phase by contributing to the minimum required surface and air distance between the arcs produced by adjacent switches and is not required to withstand the mechanical stresses which would be imposed on a fuse clipload contact cantilever mounted thereon, it may be narrow, thereby minimizing the axial length of the housing which would otherwise be required.

In the variant of FIG. 5, a separate adapter or insert 60 is shown as being inserted in the slot 36 of the fuse clip in order to accommodate the blade 61 of a fuse of a lower rating so that a single load contact-fuse clip component can be utilized for a wide range of current ratings. The adapter 60 has an apertured horizontal wall 62 and a depending wall 64 positioned in blade receiving slot 36 and provides a formed projection 65 to position the fuse blade in the slot 36 and is secured in position by screws 46.

The variant illustrated in FIG. 6 is illustrative of a modified form of the invention wherein the rotor 14 comprises a single blade rotor 14a and the load contact is formed of a pair of spaced

parallel legs

20, 20a for receiving the single blade 14a therebetween. The modified load contact of this variant is supported by the support member 44 in the same manner as with the other design so that no modifications of the housing or change in the assembly of the load contact in the housing is required.

FIG. 6 also illustrates another variant of the design wherein a fuse is not used in the switch. A terminal 66 is connected directly to the load contact by a stud 68 and the fuse clip portion is eliminated.

From the foregoing, it is apparent that this invention provides an improved adaptable, high performance, combination load contact-fuse clip unit suited for use in a wide range of switch ratings and variants wherein the housing may have a low profile and does not need to be modified for the several variants. It is further apparent that the forces imparted to the housing by the support of the combination load contact-fuse clip unit are significantly reduced from designs heretofore used and do not involve any cantilever mounting thereof.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

We claim:

1. For use in a heavy duty rotary switch having an insulated housing including walls forming a switching chamber and journalling a rotor having a switching blade mounted thereon for rotation therewith to open and close an electric circuit, the improvement comprising, in combination:

A. a conductive strap formed of a unitary strip of metal bent into a generally S-shaped configuration to provide a load contact portion engageable with the switching blade and a fuse clip portion defining a slot for receiving a fuse terminal;

B. a support plate affixed to the housing to span the walls of the switching chamber;

C. mounting means engaging said strap intermediate its load contact and fuse clip portions to mount said strap to one side of said plate; and

D. a conductive metal insert positioned in said slot to adapt said fuse clip portion for a smaller sized fuse terminal, said insert affixed to said strap to said mounting means.

2. The improvement defined in claim I, wherein said load contact and fuse clip portions of said strap are positioned below said support plate, and said fuse terminal receiving slot opens upwardly, said support plate being notched in the area above said slot to allow the insertion and removal of a fuse terminal through the laterally extending plane of said support plates.

Claims

1. For use in a heavy duty rotary switch having an insulated housing including walls forming a switching chamber and journalling a rotor having a switching blade mounted thereon for rotation therewith to open and close an electric circuit, the improvement comprising, in combination: A. a conductive strap formed of a unitary strip of metal bent into a generally S-shaped configuration to provide a load contact portion engageable with the switching blade and a fuse clip portion defining a slot for receiving a fuse terminal; B. a support plate affixed to the housing to span the walls of the switching chamber; C. mounting means engaging said strap intermediate its load contact and fuse clip portions to mount said strap to one side of said plate; and D. a conductive metal insert positioned in said slot to adapt said fuse clip portion for a smaller sized fuse terminal, said insert affixed to said strap to said mounting means.

2. The improvement defined in claim 1, wherein said load contact and fuse clip portions of said strap are positioned below said support plate, and said fuse terminal receiving slot opens upwardly, said support plate being notched in the area above said slot to allow the insertion and removal of a fuse terminal through the laterally extending plane of said support plates.