US2738399A - Fusible electric switch unit - Google Patents

Description

March 1956 H. J. HAMMERLY FUSIBLE ELECTRIC SWITCH UNIT Filed Aug. 18

Inventor": Herman J. Hammer-Lg, 1 W

H is Attorney.

United States PatentO 2,738,399 FUSIBLE ELECTRIC SWITCH UNIT Herman I. Hammerly, Plainville, Conn., assignor to General Electric Company, a corporation of New York Application August 18, 1953, Serial No. 374,925

4 Claims. (Cl. 200-163) My invention relates to improved fusible electric switch units.

It is common practice to use a bridging contact of U-shape in fusible disconnect switches of large rating. These structures are usually somewhat complex and expensive and not well suited to smaller switches which are used, for example, in housing wiring systems. The present invention has for an important object the provision of a simplified support and actuator for the bridging contact and also an improved and simplified support for the stationary contacts and terminals of a switch unit of this type.

It is another object of my invention to provide a novel contact structure which insures a quick make upon contact closure without the complication involved in a snap action activating mechanism.

Further objects and advantages will become apparent as the following description proceeds, reference being had to the accompanying drawing, and its scope will be pointed out in the appended claims. In the drawing, Fig. 1 is a front elevational view of an enclosed fusible switch unit embodying my invention; Fig. 2 is an enlarged elevational view of the unit of Fig. 1 with the cover removed; Fig. 3 is an enlarged sectional view taken along the line 3-3 of Fig. 1; Fig. 4 is an exploded view in perspective showing the various parts of the switch unit; Fig. 5 is a sectional view taken along the line 55 of Fig. 2 and showing the switch parts in open position and Fig. 6 is a similar view showing the switch parts in closed position.

Referring now to the drawing, I have shown my invention embodied in a fusible switch unit mounted in a general purpose metal enclosing case 1 having a hinged cover 2 provided with an elongated slot 3 to receive the operating handle 4 of the switch unit. The fuse block and switch body are, in the preferred form of my invention illustrated, provided by a single molded body of insulating material 5 secured against the back of the case 1 by means of a lug 6 formed integrally with the back of the case and by a screw 7 having threaded engagement with the case. Since the base is recessed from both the front and back to receive conducting parts of the switch unit, it is insulated from the case 1 by means of a sheet 8 of insulating material interposed between the base 5 and the case 1.

The particular embodiment of my invention illustrated is adapted to fuse and switch two conductors. In order to facilitate its application to two single phase circuits or one two phase three wire circuit, a neutral or ground bus is provided by the conducting strap 9. The remainder of the structure, with the exception of the operating handle, is duplicated about a vertical center line as viewed in Fig. 2 and in the interests of simplifying the description only one half will be described.

The base 5 is molded to provide a novel supporting and housing structure for the terminals and contacts of the switch unit. As illustrated the base is recessed from both the front and back to provide supporting walls 10 and 10 extending generally parallel to the back of the casing and intermediate the front and back of the insulating base 5. The wall 10 is also accessible from the upper edge of the base and provides a support for a U-shaped conducting member 11 to provide one of the line terminals of the device as well as one of the stationary contacts 12 of the switch. The U-shaped member is slipped over the wall 10 and held in position by a binding screw 13 and also is adapted for connection to an external circuit conductor. The wall 10 is integral with a wall portion 14 extending toward the front of the base 5 and providing a guide for one arm of the U-shaped movable or bridging contact 15.

In a similar manner the wall 10' supports the shell and center terminals 16 and 17 respectively which are adapted to receive a plug fuse and a terminal strap 18 which terminates in a curved stationary switch contact 19. As best illustrated in Figs. 5 and 6 the inturned flange at the bottom of the shell terminal is clamped against the wall 10' by the center terminal which is in the form of a rivet 17 and washer 17. The rivet also secures the strip 18 to the back of the wall 10. The center contact is insulated from the shell contact by a suitable insulating washer 17 The second terminal 16 of the switch device is provided by a conducting strap terminating at its inner end in a washer 16" clamped between the insulating washer 1t) and the inturned flange of the shell terminal 16.

A wall section 20 extends from the inner end of the wall 10 toward the front of the casing and partially encloses the shell terminal and also provides a guiding surface for the other leg of the U-shaped contact 15. Inter mediate between the stationary contacts 12 and 19 is an insulating barrier 21 which extends substantially beyond the plane of the stationary contacts to provide an elongated path for any are between the stationary contacts thus facilitating the interruption of current upon withdrawal of the U-shaped bridging contact. As illustrated in Fig. 4 the wall 21 is supported from side walls 23 and 24 which cooperate with the walls 14 and 20 to provide a substantially closed rectangular switching chamber.

As illustrated in Figs. 5 and 6, the walls 14 and 20 are recessed at 25 to receive the ribs 26 which are pressed out of the opposed arms of the U-shaped switching member. These ribs are spaced from the contact portions of the arms and serve to deflect the arms inwardly away from the stationary contacts until the movable contact is fully inserted at which time the projections 26 drop into the recesses 25 allowing the opposed arms of the movable contact to engage the stationary contacts 12 and 19 with a quick make action independently of the speed of movement of the handle 4. As illustrated the walls 14 and 20 preferably converge a little toward the contacts 12 and 19 to gradually move the arms of the movable contact 15 together as the contact is moved toward closed position.

The U-shaped member is operated between the positions shown in Figs. 5 and 6 by means of a toggle type operating member 4 supported from the integral bearings 27 formed on the base 5 by means of a pivot pin 28. An integral hub 29 extends from the side of the switch operating member 4 at a point spaced from the pin 28 and the U-shaped contact is mounted on this hub. The opposed legs of the contact are indented as shown at 30 so that it substantially surrounds the hub 29. It is apparent that as the toggle member is moved about the pin 28 the movable contact is inserted between and withdrawn from the stationary contacts 12 and 19.

It will be seen that each of the bridging contacts 15 is extremely simple in construction, being formed of straight strip metal stock deformed only in a direction generally transverse to its major fiat surfaces, so that it may be readily fabricated as by rolling, stamping, bending, etc. 'The contacts are readily assembled, moreover, by merely sliding them onto the hubs 29' and then inserting them in the switching chambers before the handle shaft 28 is assembled. The shaft 28, ,when in place, serves to. retainthebridging contacts.15.in operative positionsince. it limits the possible movement of the handle 4 to rotational movement, and in either. extreme. position,-as

indicated in Figures ,5 and -6, the contacts15 do not fully Moreover, as will,

emerge from the switching-chamber. be seen by reference to Figures .2 and 5, although the bridgingcontact 15 is still partially placed within the recess in the open position, the ribs 26 areuplainly visibleswitch as shown in Figs. 5 and 6 with an indentation32 formed inthe cover. These openings 31 aresuitable to receive a padlock or other locking. means which engages the indentation 32 to restrain the operating member from movement. 4

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing fromv the invention, and that it is intended by the appended claims to cover all such changes and modifications as. fall within the truespirit and scope of the invention.

What 1 claim as new and desire to secure by Letters 'iatent of the United States is: V

1. An electric switch unit comprising a pair of stationary contacts, a base of insulatingv material supporting said contacts in spaced and insulated relation, a U-shaped contact, an operating member pivoted on said base, and a hubsupported on said operating metnber extending between the opposed arms of saidU-shaped contact, said.

generally cylindrical hub projecting therefrom generally a parallel to said axis and eccentric th'ereto, a. generally U-shaped'resilient movable bridging contact, means guiding said movable contact for reciprocatingmovement along a substantially rectilinear path into and out of engagement with said stationary contacts, said U-shaped resilient contact being formed of relatively thin strip material, the sides of said contact being indented adjacent the bight thereof toward each other to provide a generally cylindrical bearing whereby said contact is adapted to be pivotally supported on said hub to be reciprocated thereby along said path into and out of engagement with saidstationary contacts.

3. An electricswitch unit comprising-a base of insulating material having anelongated generally rectangular recess therein, two relatively stationary contacts carried by said base and having contact'portions extending into said recess, a manually operable handle member pivotally supported on an axis on said base and having a generally cylindrical hub projecting therefrom generally parallel to said axis and eccentric thereto; a generally U-shaped resilient movable bridging contact formed 'of relatively thin strip material, the sides ofsaidtcontact being indented adjacent the bight thereof toward. each other to provide a hollow generally cylindrical bearing, the said hub extending into said bearing to-provide'a' pivotal connection between said handle and said contacts,

and said contact extending within saidrecess, the walls of said recess serving to guide said contact for reciprocating movement into and out of engagement with said stationary, contacts.

4. The electric switch unit as set forth in claim 3, said handle member being movable about its pivotal axis between .an on position wherein :said U-shaped contact is in engagement with said stationary contacts, and-an 1 off position wherein said U.-shaped contact is out of engagement with said stationary contacts, said U-shaped contact having a deformed portion adjacent an end there of remote from said bight, said deformed portion being visible from the front of said. switchwhen said handle member is in said oil position, and saidcontact having at least a portion thereof remaining within said recess when said handle is in said off position.

References Cited in the tile of this patent UNITED STATES PATENTS 2,253,968 Cook .Aug.. 26; 1941 2,492,101 Landmeier Dec. 20, 1949 2,494,315 Rowe Jan. 10, 1950

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