US1408690A - Electric switch - Google Patents

Description

P. H. CHASE.

ELECTRIC SWITCH.

APPLICATION FILED JUN; 23. 1919.

Patented Mar. 7, 1922.

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AYQAWGJV O 0 O O BZ HINgEkTOR P. H. CHASE.

ELECTRIC SWITCH. APPLICATION FILED JUNE23, I919.

Patented Mar. 7, 1922.

2 $HEETSSHEET Z.

INVENTOR NEY UNITED STATES PATENT OFFICE.

PHILIP H. CHASE, OF CYNWYD, PENNSYLVANIA, ASSIGNOR TO SEARS B. CONDIT, OF BROOKLINE, MASSACHUSETTS.

ELECTRIC SWITCH.

Application filed June 23,

To all whom. it may concern:

Be it known that I, PHILIP H. CHASE, a citizen of the United States, and a resident of Cynwyd, in the county of Montgomery and State of Pennsylvania, have invented an Improvement in Electric Switches, of which the following is a specification.

Certain features of this invention are disclosed in copending applications of George A. Burnham, Serial No. 354,920, filed Jan. 29, 1920, and a divisional application thereof, Serial No. 420,513, filed Oct. 29, 1920, which applications are assigned to Sears B. Condit.

This invention relates to electric switches,

and with regard to certain more specific fea tures, to a device for use in connection with oil switches, or oil circuit-breakers.

Among the objects of the invention may be noted the provision of a simple and ef fective device for increasing the strength of the switch, particularly its resistance to the shocks accompanying the flow of heavy currents such as those incident to short circuits; the provision of an expansion chamher for absorbing part of the fluid pressure occasioned by gases and the heating or volatilizing of oil at the arcs, when the circuit is being broken; the provision of a tank, shell or casing so constructedas to minimize the tendency of the casing to burst under the influence of excessive pressure thus occasioned; and the provision of features conducive to safe and eflicient operation of the switch.

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

The invention accordingly consists in the features of construction, combinations of elements and arrangement of parts which will be exemplified inthe construction hereinafter set forth, and the scope of the application of which will be indicated in the following claims.

In the drawings, in which is illustrated one of various possible embodiments of the invention,

Fig. 1 is a vertical section of a preferred type of switch;

Fig. 2 is a top view of Fig. 1; Fig. 3 is a vertical section on the line 33,

Fig 2;

ig. 4 is a horizontal section on the hue 4-4, Fig. 1;

Fig. 5 is a vertical section on the line 5-5, Fig. 6, showing a modification;

Specification of Letters Patent.

Patented Mar. *7, 1922.

1919. Serial No. 306,098.

Fig. 6 is a vertical section of said modification;

Fig. 7 is a horizontal section on the line 7-7, Fig. 8, showing a second modification;

Fig. 8 is a vertical section of said second modification.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Referring now more particularly to Figs. 1 to 4 of the drawings, there is illustrated a single-pole electric switch, of the type known commercially as an oil switch, comprising a casing 1, in the upper portion of which are mounted tw'o insulating bushings 3, a for the terminals 6, 7, connected respectively to the fixed contacts 9, 10 Mounted centrally in the casing for vertical movement with respect thereto, is the operating rod 12 carrying the conducting yoke 14 at either end of which are mounted the movable contacts l6, 17, here shown as provided with arcing tips. When the rod is moved to its upper position by suitable operating means, the circuit across the two fixed contacts is closed. hen the rod is moved 1 downwardly, this circuit is opened. At the moment of downward motion, from the time the contacts begin to separate, an arc is formed between each fixed contact and its corresponding movable contact if there is any current passing through the circuit at the time. Under ordinary conditions these arcs are extinguished by the oil, which ordinarily fills the tank up to about the normal level 19. When the current is above normal values. however, as occurs, for example, when abnormal conditions prevail in the external circuit, the oil does not readily extinguish the arcs, and in many instances the heat generated by the arcs is great enough to volatilize the oil, and generate pressure that forces the oil out of the easing, if there is opportunity for it to do so, or even to break or burst the casing.

In order to overcome these disadvantages, the present invention provides several features of construction which in many instances may be utilized separately or in various combinations with one another.

One of these features is the provision of an auxiliary expansion chamber 21 shown in this instance in the upper part of the casing, preferably separate from the main expansion chamber 23 but communicating with the oil at or near the bottom of the tank circuit cause the pressure of the oil in the lower part of the chamber to rise above normal, the oil is thus free to travel upwardly through the annular passage 25 into the auxiliary expansion chamber 21, the pressurein the latter being relieved if desired by a baflied outlet 29 (Figs. 1 and 2), shown more in detail in Fig. 3. This may be similar in construction to the baflled outlet 31 connecting the main expansion chamber 23 with the external atmosphere. The outlets are preferably baflled, in order to decrease the liability of loss of oil through the outlets when the pressure within the casing forces air and other gases out.

The inner wall 27, as indicated in Fig. 1, is broken away at a point above the bottom of the tank, to permit flow of oil from the inner part of the tank outwardly into the annular passage 25. The heat generated by the arcs causes pressure to be exerted upon the oil below the arcs as well as above the 'arcs, and this auxiliary expansion chamber is particularly effective in relieving the pressure below the arcs, that is, the pressure exerted downwardly. The main expansion chamber takes care of the pressure and movement of oil and gases in an upward direction, that is, above the arcs.

1n orderto further relieve the tank of the excessive mechanical shocks occasioned by the generation of abnormal pressure, this invention provides a tank'bottom 33 (Figs. 5 and 6) of curved shape, with its highest point or apex 34 substantially in line with the operating rod 12 or midway between the contacts 9, 16 and 10, 17. The tank then slopes downwardly away from this apex in either direction, and then slopes preferably upwardly as it approaches the side wall 35 of the casing, as indicated in Figs. 5 and 6. With this construction the downward pressure and flow of oil is directed or reflected outwardly and upwardly, whereas with a flat bottom there is greater tendency for the oil to blow the bottom out of the tank when abnormal volatilization and pressure occurs at the arcs.

\Vith the inner-wall and auxiliary expansion chamber construction above described, this deflecting bottom assists in directing the oil upwardly through the annular passage 25. If these features of inner wall and auxiliary expansion chamber are omitted, the deflecting bottom is'still useful in lessening the tendency of the bottom to be blown outward; in such case the deflecting construction increases the circulation of oil upwardly along the outer wall of the easing and thus relieves the pressure at thebottom, the oil passing upwardly into the single expansion chamber; whereas if an auxiliary expansion chamber is provided, the oil passes into the latter.

The side wall may be provided with a reinforcing and deflecting plate 37, shown in Figs. 7 and 8. This plate serves to strengthen the side wall of the casing, and also to direct outwardly moving fluid into a downward and upward direction. The apex 39 of the plate is preferably adjacent the arcs, as is indicated in Fig. 8.

While a single-pole switch is illustrated herein, the invention is obviously applicable to multiple-pole switches.

Means for operating the switch through the rod 12 is not shown, as it forms per se no feature of the present invention. Such means may be manual or mechanical.

1 My invention is obviously not limited to the embodiments herein described and illustrated.

I claim:

1. An electric switch combining relatively movable contacts, a casing in which said contacts are mounted, an insulating fluid in the casing, the Surface of said fluid being normally at a single level, and fluidpressure-relieving means adapted to direct fluid moving downwardly in the easing into an outward direction, said means comprising a curved deflecting surface against which the downwardly moving fluid strikes, and by which said fluid is directed into an outward direction 2. An electric switch combining relatively movablecontacts, a casing in which said contacts are mounted, an insulating fluid in the casing, and a curved bottom for the casing adapted to direct downwardly moving fluid into an outward direction and thence into an upward direction.

3. An electric switch combining fixed contacts, mOXHblB contacts cooperating therewith, a casing in which said contacts are mounted, an insulating fluid in said casing,

an expansion chamber above the fluid level,

an auxiliary expansion chamber, and means adapted, upon the formation of an arc at the contacts, to direct fluid away from the contacts and toward said auxiliary expansion chamber.

4t. An electric switch combining relatively movable contacts, a casing in which said contacts are mounted, an insulating fluid in the casing, a cover for the casing, an inner wall between the contacts and the casing, a cover extending across the top of said inner wall to enclose the space within said inner wall and form a main expansion chamber therein, the space above the fluid level and outside said cover and within the cover of the casing forming an auxiliary expansion chamber.

5. An electric switch combining a casing an inner wall therein, contacts mounted within said inner wall, and an insulating ana-sec fluid in the casing and normally under mospheric pressure, the space outside said inner wail and above the fluid level therein forming an expansion chamber.

6. An electric switch combining casing, an inner wall therein, relatively movable contacts within said inner wall and insulated therefrom, an insulating fluid in the casing and normally at a single level, the space above the fluid level and outside said inner wall and within the cover of the casing forming an expansion chamber.

7. An electric switch combining acasing, and relatively movable contacts therein mersed in an insulating fluid, the casing having a portion projecting inwardly toward said contacts to direct away from the contacts the fluid forced against said portion when an arc is formed at the contacts.

8. An electric switch combining a casing, and relatively movable contacts therein immersed in an insulating fluid, the casing having an inner wall rovided with a portion projecting inwar ly toward said contacts to direct away from the contacts the fluid forced against said portion when an arc is formed at the contacts.

9. An electric switch combining relatively movable contacts, a covered casing in which said contacts are mounted, an insulating fluid in the casing, and a perforated inner wall between the contacts and the casing, the space above the fluid level and outside said inner wall nd within the cover of the casing forming an. expansion chamber, the fluid that is directed downwardly upon the formation of arcs at the contacts passing upwardly through the passage between inner wall and casing and into said expansion chamber..

10. An electric swiitch combining relativel mova'ble contacts, a covered casing in whic said contacts are mounted, an insulating fluid in the casing, a curved bottom for the casing adapted to direct downwardly moving fluid into an outward direction, an inner wall between the contacts and the casing, a cover extending across the top of said inner wall to enclose the space heneath said inner wall and forming a main expansion chamber therein, the space above the fluid ievel and outside said cover and within the cover of the casing forming an auxiliary expansion chamber, the fluid directed downwardly upon the formation of arcs at the contacts passing upwardly through the passage between inner wall and casing and into said auxiliary expansion chamber.

11. An electric switch combining a pair of fixed contacts, a pair of movable contacts cooperating therewith, a casing in which said contacts are mounted, oil in the casing, an expansion chamber in said casing, a deflecting bottom for the casing adapted to direct downwardly moving oil into an outward direction and thence into an upward direction, an inner wall extending around the casing between the contacts and the casing and having a portion extending toward the arcs to direct u wardly and downwardly the fluid flowing i rom said arcs toward said inner wall, a cover extending across the top of said inner wall to enclose the space beneath said inner wall and forming said expansion chamber therein, the space above the oil level and outside said cover and within the cover of the casing forming an auxiliary expansion chamber, the oil directed downwardly upon the formation of arcs at the contacts passing upwardly through the annularpassage between inner and outer walls and into said auxiliary expansion chamber, and outlets permittin passage of air between said chambers and atmosphere.

12. An electric switch combining a casing, an expansion chamber therein, relatively movable contacts within said chamber, an insulating fluid in which said contacts are immersed, a second expansion chamber in said casing, communicating with the first chamber, and automatically repeatedly operative means operable independently of movement of said contacts, for directing fluid from the first chamber to the second chamber to rclieveany abnormal fluid pres sure in the first chamber.

In testimony whereof, I have signed my name to this specification this 21st day of June, 1919.

PHILIP CHASE.

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