US2571951A - Electrical apparatus - Google Patents

Description

Oct. 16, 1951 .w, SCHAELCHLIN 2,571,951

ELECTRICAL APPARATUS Filed Sept. 9, 1949 Fig.5.

Fig.2. I 6 5 :p

2e A u I Fig 6 WITNESSES: INVE NTOR 4 W Walter Schoelchlin. f? BY ATTORN EY Patented Oct. 16, 1951 ELECTRICAL APPARATUS Walter Schaelchlin, Buffalo, N. Y., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 9, 1949, Serial N 0. 114,739

1 Claim.

This invention relates, generally, to switching devices and more particularly to an arcextinguishing arrangement applicable in electrical switching devices.

One object of this invention is to provide an arc-extinguishing structure for an electric switch which is simple in its elements and effective in operation.

Another object of this invention is to provide an arc-extinguishing structure for an electric switch which is compact in arrangement.

A further object of this invention is to provide an electric switching structure of the character referred to which produces'a highly concentrated magnetic field for extinguishing the are which is drawn when the contacts are open.

An ancillary object of this invention is to provide a magnetic blow-out structure for an electric switch which requires a minimum of tools and time for assembly.

A further ancillary object of this invention is to provide a magnetic blow-out structure for an electric switch of such design that it will not tend to cause switch operation under conditions of shock.

The foregoing statements are merely illustrative of the various aims and objects of this invention. Other objects and advantages will become apparent upon a study of the following disclosure when considered in conjunction with the accompanying drawing, in which:

Figure 1 is a side view partially in section of an electric switch embodying the principles of this invention;

Fig. 2 is a plan view partially in section of the switch structure illustrated in Figure 1;

Figures 3 and 4. illustrate details of the permanent magnetic blow-out structure; and

Figures 5 and 6 illustrate one of the two pole pieces used in the magnetic blow-out structure.

The application of this invention is demonstrated in Figures 1 and 2 in connection with a cam operated switch. It will be appreciated, however, that this invention is applicable to all types of switching devices involving a moving contact and a stationary contact in which the arc drawn between the contacts upon actuation of the movable contact from engagement with the stationary contact is to be extinguished by means of a magnetic field.

Referring now to Figures 1 and 2, the switch assembly is supported upon a pair of non-magnetic bars I and 2. The upper bar I supports the stationary contact assembly generally designated 3 while the lower bar 2 supports the movable contact assembly which is generally designated 4. The non-magnetic bars I and 2 are supported between end frames forming a partof the switch housing. Only one of these end frames is shown, and it appears in Figure I wherein it is designated by the reference character 5. Each of the non-magnetic bars I and 2 is disposed within an electrical insulating jacket, that for the bar I being designated 6- and that for the bar 2 being designated I.

The stationary contact assembly 3 together with the blow-out structure is supported entirely upon the bar I and the assembly includes a pair of permanent magnets 8 and 9 which are illustrated in Figures 3 and 4. These magnets 8 and 9 are of arcuate configuration externally, and are provided with suitable recesses in the confronting faces thereof to straddle the insulating material 6 upon the bar I. In this position the magnet assembly substantially defines a circle. As illustrated in Figure 4, one face of each of the magnets is a south pole while the other face is a north pole. In assembled position, corresponding pole faces of the magnets lie in a single plane. The magnets are secured in position about the bar I by means of a clamp I0 which is of rectangular configuration and which is provided with a circular opening therein to encompass the permanent magnet assembly. One side of the clamp is reduced in crosssection at II to provide a flexible section to allow for some springing apart of the clamping surfaces of the clamp so that the clamp may be conveniently positioned around the permanent magnets. At the opposite side of the clamp from section II, a clamping bolt is provided. This bolt is designated I2 and is equipped with a nut I3 which is drawn down to tighten the clamp about the permanent magnets and secure the assembly upon the bar I.

Pole pieces I5 and I6 are provided adjacent each pole face of the permanent magnets. The pole faces of the magnets define substantially parallel planes and the pole pieces disposed thereagainst extend in one direction beyond in spaced relation with each other. The pole pieces are securely clamped against the permanent magnets by means of spacers I l disposed on each side of the pole piece assembly in concentric relation with the bar I. These spacers extend between the end frames 5 and/or between adjacent switch structures corresponding to the one presently being described and thereby provide a secure assembly of the switch structure. A stationary contact I8 is supported between the confronting faces of the pole pieces l5 and 16 with the plane of the contact surface substantially paralleling the magnetic field between the pole pieces. The support means for the stationary contact l8 comprises a contact strip l8 which extends up the face of the clamp between the pole pieces and along the top of the clamp as viewed in Figure 1 where its extremity is secured beneath the nut l3. The contact strip 19 may be securely soldered or brazed or otherwise suitably fastened on the clamp ID to provide good electrical contact therewith and a terminal in the form of an extension of the clamp is provided at 20 to afford an electrical connection from an external circuit to the contact [8. The pole pieces l5 and it are preferably protected by means of an electrical insulating and heat resisting material indicated at 2| and 22 respectively, for poles l5 and 16. These insulating pieces may be of the form of sleeves of asbestos or other suitable material which slip over the ends of the pole pieces.

The movable contact structure Al is entirely supported upon the lower bar 2 as seen in Figure 1. In this assembly a clamp 24 is provided about the bar 2, this clamp terminating in a terminal 25. The movable contact arm 26 is pivotally mounted at 27 on the clamp 2G and includes an upper contact carrying arm 28, the extremity of which extends into the space between the pole pieces and IS. The movable contact 29 of this assembly is securely fastened to a contact strip 30 which, in turn, is secured to the upper contact arm 28. A lower extension 31 of the movable contact arm is provided with a roller 32 which follows the surface of a cam 33 which is pivotally mounted between the side frames 5 and which may be actuated by any suitable means, not shown. Cam 33 is provided with suitable recesses 34 illustrated in dot-dash outline for an alternative position of the cam and the roller 32 is shown in dot-dash outline in the recess. This recess is in the peripheral edge of the cam affording a space into which the roller 32 of the movable contact arm 26 may move, providing for pivotal movement of the contact arm in a clockwise direction as viewed in Figure 1 so that the movable contact 29 may move into a position engaging the stationary contact Hi. This completes a circuit between the terminals 2% and 25 through a flexible shunt 35 which connects the terminal 25 with the lower part 3| of the contact arm 26. A clockwise bias is applied to the contact arm 26 to assure positive engagement of the roller with the cam along the irregular cam sur- 7 face. This bias is provided by a compression spring 36 which is disposed between the terminal strip 25 and the lower arm 31 of the movable contact arm.

The small powerful permanent magnets 6 and 8 produce a magnetic field across the pole pieces 15 and I6 in a direction substantially normal to the path of the are which is drawn at the time the contacts 29 and [B are separated. This is a uniform and unidirectional magnetic field and its extinguishing the arc is very compact in nature and by reason of its concentric mounting with respect to the mounting bar I, has no influence,

- in an adverse sense, upon the opening or closing of the switch.

While but one embodiment of this invention has been illustrated and described, it will be apparent to those skilled in the art that numerous modifications may be made in the details of the illustrated structure without departing from the principles and scope of this invention. Accordingly, it is intended that the foregoing disclosure and illustrations made in the drawing shall be interpreted only as illustrative and not construed in a limiting sense.

I claim as my invention:

A magnetic blowout structure for switches comprising in combination, a mounting bar of nonmagnetic material, a pair of U-shaped permanent magnets straddling said bar from opposite sides thereof with corresponding pole faces lying in the same plane transversely of said bar, clamp means of non-"magnetic material disposed about said permanent magnets securing said permanent magnets against said bar, a pair of fiat rectangular pole pieces of magnetizable material having openings therein adjacent corresponding extremities to clear said bar, said pole pieces being respectively disposed against the pole faces of said permanent magnets and extending therebeyond in one direction in spaced relation, means securing said pole pieces against said pole faces, a contact strip secured to said clamp means and extending along said clamp means between said spaced pole pieces, and a contact secured to said contact strip between said spaced pole pieces, the plane of the contact face of said contact lying substantially parallel to the magnetic field be tween said spaced pole pieces.

WALTER SCHAELCHLIN.

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

UNITED STATES PATENTS Number Name Date 1,010,620 Crumpton Dec. 5, 1911 1,362,003 James Dec. 14, 1920 1,511,332 Harrison Oct. 14, 1924 1,816,894 Burnham Aug. 4, 1931 2,411,893 Peters Dec. 3, 1946

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