US3143612A

US3143612A - Electric circuit breakers of the type which are temporarily pneumatically opened

Info

Publication number: US3143612A
Application number: US167034A
Authority: US
Inventors: Nijland Elizabeth Hidde
Original assignee: Co2 Nv
Current assignee: Co2 Nv; N V "co2"
Priority date: 1961-01-24
Filing date: 1962-01-18
Publication date: 1964-08-04
Anticipated expiration: 1981-08-04
Also published as: BE612865A; NL120011C; DE1182726B; NL260393A; GB930987A; CH406359A

Description

4, 1954 H. A. HIDDE NIJLAND 3,143,612

ELECTRIC CIRCUIT BREAKERS OF THE TYPE WHICH ARE TEMPORARILY PNEUMATICALLY OPENED Filed Jan. 18, 1962 INVENTOR HENDR\K A. HIDDE. NHL-AND ATTORNEYS nied W3 P t? Hidde Nijland, executrix of said Hendrik A. Hidde' Nijland,'deceased, assignor to N.V. CO2, Utrecht, Netherlands, a limited company of the Netherlands Filed Jan. 18, 1962, Ser. No. 167,034 Claims priority, application Netherlands Jan. 24, 1961 p v .6 Claims. (Cl. 200-82) c The invention relates to an electro-circuit breaker of the type, which is temporarily pneumatically opened and comprises a fixed contact and a movable contact forced against said first contact by a spring, said movable contact being mounted to be separated from said fixed contact by a piston which is mounted for reciprocation in a cylinder and is moved when one side of the piston is exposed to gas, of which the pressure has reached a predetermined value, said piston being adapted to move with respect to the movable contact freely along a predetermined distance and being forced by a spring into a position ofrest, in which position said piston is exposed to the gas pressure with a portion of its active area only, the arrangement being such as to permit the entire active area of the piston of being exposed to the gas pressure after the piston has been moved by the gas out of its position of rest againstsaid spring and before it is coupled with the movable contact.

An electric circuit breaker of this type is described in the US. Patent No. 2,500,429. Inthis known circuit breaker the cylinder and the piston have additional portions with a reduced diameter. A piston having such a reduced portion requires an axial dimension which is twice the dimension of a normal piston as to ensure areliable seal in the two parts of different diameters of the cylinder. In order to obtain an accurate fit of the piston in the two partsof the cylinder the piston body and the cylinder must be machined very accurately and in different areas thereof the tolerances of the variations of the dimensions of said bodies must be keptvery small. I In this knowncircuit breaker the lost motion of the piston, which depends on the axial dimension of the portion of the piston having the reduced diameter, extends through a rather great distance.

The invention has for its object to provide an electric circuit breaker of the type referred to, in which both the cylinder and the piston consist of one active cylindric part only, so that the manufacture is considerably simplified and further advantages to be described hereinafter are obtained. It consists in that the active area of the piston or the cylinder end wall facing said piston area is provided with an annular rib having a diameter which is smaller than that of the piston and a ring of elastic material is provided on said cylinder end wall or said piston area, respectively, said cylinder end wall and the elastic ring, if provided on said wall, having exclusively inside or outside the annular rib one or more passages for the supply of gas under pressure, said rib and said elastic ring being pressed against one another in a gas tight manner by the spring loading the piston, when the latter is in its position of rest. In this construction not only the axial dimension but also the lost motion of the piston may be made smaller than those of the piston having a reduced portion, so that the cylinder may have a smaller axial dimension and the time passed between the point of time, at which the gas under pressure is supplied, and that, at which the switching-otf operation takes place, will be shorter.

To obtain a reliable seal between the cylinder spaces separated by the annular rib and the elastic ring it is recommended to give the annular rib such a cross-sectional 3,143,612 Patented Aug. 4, 1964 'ice profile as to have said rib pressed into the elastic ring with a sharp edge. Said cross-sectional profile may have the shape of a triangle of which the base faces the piston.

In order to prevent that due to gas leaking through the seal formed by the rib and the ring of elastic material the pressure under the entire active area of the piston would rise, when the pressure under the smaller piston area increases and thereby the piston would be set in motion before the gas pressure would have reached the desired value, the cylinder space, in which the gas pressure becomes last active, may be connected with the atmosphere by a vent, when the piston is in its position of rest, said' vent being closed, as soon as the piston is exposed with its entire active area to the gas pressure. This vent enables the pressure under the piston area to remain equal to that of the atmosphere as long as the two parts of the active cylinder chamber are separated from another by the annular rib. This vent may open into the inactive cylinder chamber and 'may' be closed by the piston itself. In that case an additional valve for closing the vent is dispensed with.

The invention will be elucidated with the aid of the accompanying drawing, which diagrammatically illustrates by way of example an .axial sectional View of the essential part of an electric circuit breaker of the type, which is temporarily pneumatically opened.

In the drawing 1 is a fixed contact provided with a terminal strip 2 for the connection to the outer circuit. Cooperating with said fixed contact is a movable contact 3 which in the present case closes an opening 4 for the discharge of extinguishing gas. The movable contact 3 has astem 5, which is passed through the'bottom 6 of a cylinder 7 and through a fixed contact ring 8 also provided with a terminal strip 9.

A piston 10 is loosely mounted on the stem 5 in the cylinder 7.. Said piston is provided with an annular rib 11 having a triangular cross profile and in its position of rest said piston is pressed with its rib against a ring 13 of elastic material by a'spring 12. The elastic ring 13 lies on the cylinder bottom 6. In said position of rest the active cylinder chamber under the piston 10 is divided into two separated

parts

14 and 15. The part 14 of said cylinder chamber communicates through passages 16 made in the cylinder bottom 6 with the switching chamber 17, to which gas under pressure can be supplied through an aperture 18 made in the wall of a tube 19 of insulating materi'al: 'This tube keeps the fixed contact 1 and the ring contact 8 spacedapart and surrounds the switching chamber 17. The contact pressure between the contacts 1 and 3 is furnished by the spring 20.

When gas under pressure is admitted to the switching chamber 17 through the aperture 18, the pressure in said chamber and also in the cylinder space 14 will rise. If the force exerted on the relevant portion of the piston by the gas in the cylinder chamber 14 overcomes the force of the spring 12, which will happen when the pressure of the gas exceeds a predetermined value, the piston 10 is moved upwards and the gas under pressure is also admitted to the cylinder space 15, since the piston is lifted with its rib 11 from the elastic ring 13 and the

cylinder spaces

14, 15 are brought into communication with one another. Thereafter the piston is exposed with its entire active area to the gas pressure and owing thereto the piston is driven upwards with great force against a collar 21 provided on the stem 5 of the movable contact 3. As a consequence thereof said contact is taken along with the piston against the force of the

springs

12 and 20 and separated from the fixed contact 1, whereby the opening 4 is opened and the gas, which is in the switching chamber 17 under high pressure, is able to escape through said opening with great force, so that the are established between the contacts 1 and 3 is extinguished.

In the position of rest of the piston the cylinder space is connected by a by-pass passage or vent 22 to the chamber 23 which communicates with the atmosphere. Said. vent makes that the pressure in the cylinder space 15 is not able to rise when gas is leaking from. the cylinder space 14 into the space 15 through the seal formed by. the rib 11 of the piston 10 and the elastic ring 13 in the position of rest of the piston. However, as soon as the piston is moved upwards and gas under pressure is admitted to the cylinder space 15, the connection between the cylinder space 15 and the chamber 23 is interrupted by the piston 10, so that also in the cylinder space 15 the pressure of the gas is permitted to rise;

It is observed that it is not necessary that the piston is driven by the extinguishing gas. The pneumatic switching-off operation of the circuit breaker and the extinguishing of. the established arc may be effected independently from one another and by different fluids. The rib 11 may be provided on the cylinder bottom 6 and the ring 13 may be attached to the piston 10.

What I claim is:

1. A pneumatically openable electric circuit breaker comprising a fixed contact, a movable contact, a spring tending to force said movable contact against said fixed contact, a cylinder, a piston mounted for reciprocation in said cylinder and dividing said cylinder into an active" chamber and an inactive chamber, passages for leading and the area of the active face of the piston includes an annular rib formed on the active face of the piston and a seat of elastic material on the cylinder onto which the rib is pressed by said second spring in the position of rest of said piston.

3. An electric circuit breaker as claimed in claim 2 in which said annular rib has a cross sectional profile including a sharp edge which is pressed into said elastic seat gas under pressure into said active chamber and against an active face of said piston, a second spring tending to force said piston into a position of rest, means dividing the active cylinder chamber and the area of the active face of the piston each into two parts when the piston is in its position of rest and inoperative to so divide the piston and active chamber upon movement of the piston from itsposition of rest, the passages for supplying gas under pressure opening into one of said parts of the active cylinder chamber, and coupling means for connecting said piston with said movable contact to move the latter contact away from the fixed contact upon exposure. of the active face of the piston to gas pressure exceeding a predetermined value, said piston having a lost motion betweenits position of' rest and a coupling position in which it is connected to said movable contact by said coupling means, whereby the application of gas under pressure exceeding said predetermined value acts first on only part ofv the active face of the piston to slowly move the piston'from when the piston is in its position of rest.

. 4. An electric circuit breaker as claimed in claim 1 further comprising a vent passage connecting to atmosphere that part of the active cylinder chamber separated from the part into which the gas supply passages open,

' said vent passage being closed by the piston when the piston is moved from its rest position towards the position for coupling the piston with the movable contact. I

5. An electric circuit breaker according to claim 4 wherein said vent passage communicates with said active and inactive gas chambers, the latter being open to atmosphere.

I 6. A pneumatically openable electric circuit breaker comprising a fixed contact, a movable contact, a spring tending to force said movable contact against said fixed contact, a cylinder, a piston mounted for reciprocation in said cylinder, passages for leading gas under pressure into said chamber and against one face of said piston, a second spring tending to force said piston into a position of rest, means dividing said cylinder and the area of said one face of the piston into two active gas chambers when the piston is in its position of rest andinoperative to separate said active chamber upon movement of the piston from its position of rest, the passages for supplying gas under pressure opening intoone of said active chambers, and

its position of rest whichmovement takes up said lost motion and opens both said chamber and piston parts to coupling means for connecting said piston with said movable contact to move the latter contact away from the fixed contact upon exposure of the piston to gas pressure exceeding a predetermined value, said piston having a lost motion between its position of rest and a coupling position in which it is connected to said movable contact by said coupling means.

References Cited in the file of this patent UNITED" STATES PATENTS 693,416 Messicket a1. Feb. 18, 1902 2,091,904 Baumann Aug. 31, 1937 2,420,370 Hamilton May 13, 1947 2,556,209 Negro June 12, 1951 p FOREIGN PATENTS 1 813,229 France Feb. 22, 1937 UNITED STATES PATENT-OFFICE CERTIFICATE ()F' COR-REGTION Patent No. 3,143,612 August 4, 1964 Hendrik A. Hidde Nijland, deceased Elizabeth Hidde Nijland, executrix It ishereby eertifiedthat error appears in the. above numberedpatent -'reqiiring"correction and that the said Letters Patentshould read as corrected below."

In the grant,

lines

3 and 13, and in the heading to the printed specification, line 7, for "'C'O2, each occurrence,

read "COQ,"

Signed and sealed this 22nd day vof December 1964. L

1sEAL")- EDWARD J. BRENNER?" Commissioner of Patents n t'estifi Officer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION? Patent No. 3,143,612

Hendrik A. [-11 August 4, 1964 dde Nijland,

Elizabeth Hid It is hereby deceased, de Nijland, executrix certified that error appears in the. above numberedtpat ent reqiiringcorreetioh and that the said LettersPatent should read as cor-rectedbelow.

In the

grant lines

3 and 13, and in the heading to the printed specification, line 7, for read "COQ, -o

"'C02, each occurrence,

Signed and sealed this 22nd day of December 1964,

aRNEsT w. 4 SWIDER' Itl'e sting Officer EDWARD J. BRENNER Commissioner of Patents

Claims

1. A PNEUMATICALLY OPENABLE ELECTRIC CIRCUIT BREAKER COMPRISING A FIXED CONTACT, A MOVABLE CONTACT, A SPRING TENDING TO FORCE SAID MOVABLE CONTACT AGAINST SAID FIXED CONTACT, A CYLINDER, A PISTON MOUNTED FOR RECIPROCATION IN SAID CYLINDER AND DIVIDING SAID CYLINDER INTO AN ACTIVE CHAMBER AND AN INACTIVE CHAMBER, PASSAGES FOR LEADING GAS UNDER PRESSURE INTO SAID ACTIVE CHAMBER AND AGAINST AN ACTIVE FACE OF SAID PISTON, A SECOND SPRING TENDING TO FORCE SAID PISTON INTO A POSITION OF REST, MEANS DIVIDING THE ACTIVE CYLINDER CHAMBER AND THE AREA OF THE ACTIVE FACE OF THE PISTON EACH INTO TWO PARTS WHEN THE PISTON IS IN ITS POSITION OF REST AND INOPERATIVE TO SO DIVIDE THE PISTON AND ACTIVE CHAMBER UPON MOVEMENT OF THE PISTON FROM ITS POSITION OF REST, THE PASSAGES FOR SUPPLYING GAS UNDER PRESSURE OPENING INTO ONE OF SAID PARTS OF THE ACTIVE CYLINDER CHAMBER, AND COUPLING MEANS FOR CONNECTING SAID PISTON WITH SAID MOVABLE CONTACT TO MOVE THE LATTER CONTACT AWAY FROM THE FIXED CONTACT UPON EXPOSURE OF THE ACTIVE FACE OF THE PISTON TO GAS PRESSURE EXCEEDING A PREDETERMINED VALUE, SAID PISTON HAVING A LOST MOTION BETWEEN ITS POSITION OF REST AND A COUPLING POSITION IN WHICH IT IS CONNECTED TO SAID MOVABLE CONTACT BY SAID COUPLING MEANS, WHEREBY THE APPLICATION OF GAS UNDER PRESSURE EXCEEDING SAID PREDETERMINED VALUE ACTS FIRST ON ONLY PART OF THE ACTIVE FACE OF THE PISTON TO SLOWLY MOVE THE PISTON FROM ITS POSITION OF REST WHICH MOVEMENT TAKES UP SAID LOST MOTION AND OPENS BOTH SAID CHAMBER AND PISTON PARTS TO GAS PRESSURE.