US2247201A - Circuit breaker operating means - Google Patents

Description

June 24, 1941. A. 1.005 2,247,201

CIRCUIT BREAKER OPERATING MEANS Filed Nov. 16, 1958 Fig.1.

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43 a5 4/ 43 if A z 5 INVENTOR 9 fllfred Loos.

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Z TTORN E Patented June 24, 1941 UNITED STATES PATENT ()FFICE CIRCUIT BREAKER OPERATING MEANS Vania Application November 16, 1938, Serial No. 240,711 In Germany November 30, 1937 8 Claims.

The invention relates generally to fluid pressure operating means for circuit breakers and similar devices, and more particularly to an automatic valve for the fluid pressure operating system.

The power required to operate circuit breakers at no load is considerably lower than the power required to operate the breaker at full load, and for this reason the velocity of flow of the operating fluid will be much greater in the former than in the latter case. As a result, the operating mechanism when actuating the breaker at no load may function at such excessively high speeds that there is danger of damage to the operating mechanism or the circuit breaker.

An object of the invention is the provision of Q a fluid pressure operating means or system for a circuit breaker which will operate at a substantially constant safe speed irrespective of variations in load conditions at the circuit breaker.

Another object of the invention is the provision of a fluid pressure operating means with an automatic valve between the source of fluid pressure and the actuating piston Which automatically controls the flow of fluid to the piston in accordance with the load condition on the piston.

Another object of the invention is the provision of a fluid pressure operating means for a circuit breaker, with an automatic valve between the source of fluid pressure and the actuating piston which remains closed under no load operation of the breaker to provide for a restricted flow of fluid to the actuating piston and which automatically opens when the breaker is operated at normal or full load to provide a substantially free flow of fluid to the actuating piston.

Another object of the invention is the provision of a fluid pressure operating means with an automatic valve between the source of fluid pressure and the actuating piston which automatically controls the flow of fluid to the piston in accordance with the load condition on the piston, and which also serves to automatically damp the starting of the piston.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation together with additional objects and advantages thereof will be best understood from the following detailed description of several embodiments thereof when read in conjunction with the accompanying drawing, in which:

Figure 1 is a vertical sectional view of an automatic valve constructed in accordance with the invention.

Fig. 2 is a vertical sectional View of a modified form of valve, which is built into the end of the actuating cylinder, and

Fig. 3 is a schematic view of a portion of a fluid operating means for a circuit breaker embodying the automatic valve shown in Fig. 1.

Referring to Fig. 3 of the drawing, the reference numeral 5 designates schematically 9, circuit breaker having a stationary contact means i and a movable contact 9. The movable contact 9 is carried by an insulating rod H and is movable thereby into and out of engagement with the stationary contact means I.

The mechanism for operating the circuit breaker is shown schematically in Fig. 3 and comprises a fluid pressure actuating cylinder l3 and a fluid pressure actuating piston 15 movable in the cylinder :3. The actuating piston l5 may be connected directly to the breaker rod H through the agency of a piston rod ll and a pivoted bell crank lever it; or the piston may be connected to the control pump of a suitable hydraulic operating means for actuating the breaker rod H, as per example, a hydraulic operating means of the type shown and completely described in the copending application of Paul Dufling and D. Reich, Serial No. 235,608, flled October 18, 1938 and assigned to the assignee of the present invention.

The actuating piston is biased in an opening direction towards the left to effect opening of the breaker 5 by means of a compression spring 2| which is disposed in the right-hand end of the cylinder 13 between the piston i5 and one end wall of the cylinder. A source of fluid pressure comprising a fluid pressure container 23 is connected to the left-hand end of the actuating cylinder l3 by means of a fluid pressure conductor 25. Included in the conductor 25 is a control valve 2i. The control valve 2? is operable when moved to open position to connect the source of fluid pressure to the cylinder and admit fluid under pressure to the left-hand end of the cylinder It to cause movement of the actuating piston I5 to the right against the action of the opening spring 2'! to effect closing of the circuit breaker. The control valve 21 is also operable when moved to a closed position to cut off the supply of fluid under pressure to the cylinder l3 and at the same time to release the fluid under pressure from the cylinder through an exhaust port to the outside air thus allowing the opening spring 2| to move the piston towards the left and efiect opening of the circuit breaker.

As has previously been pointed out, the power required to operate the circuit breaker at no load is usually much lower than that required at full load. This results from the fact that during closing of a breaker under load conditions, the current begins to flow through the contacts and arcs drawn between the contacts some time before the breaker is completely closed, and this flow of current sets up considerable magnetic forces which oppose closing of the breaker. For example, in breakers having movable bridging contacts, the current flows in a curved path through the contacts and produces a magnetic field which reacts to oppose closing of the breaker. In breakers having arc extinguishers of the expansion or explosion type, the arc formed between the contacts during closing cause the generation of gas under pressure which acts on the movable contact to oppose closing of the breaker. When the breaker is closer at no load there is no current flow and hence there are no forces set up to oppose closing of the breaker. When the breaker is operated by a fluid pressure operating means the velocity of flow of the operating fluid under pressure will be much greater during no load operation than in the case of operation under load. As a result, the operating mechanism when actuating the breaker at no load may operate at such excessively high speeds as to cause damage to the operating mechanism and the breaker.

According to the present invention, the abovementioned danger is eliminated by the provision of an automatic valve 29 in the connecting means between the control valve 21 and the actuating cylinder IS. The automatic valve 29 is operable When the control valve is opened to automatically control the flow of fluid to the cylinder I3 in accordance with the load conditions on the actuating piston Hi. The automatic valve provides a restricted flow of fluid to the actuating cylinder when the breaker is operated at no load, and a substantially free flow of fluid to the cylinder I3 when the breaker is operated at full load.

Referring to Fig. 1, the automatic valve 29 for controlling the flow of fluid to the actuating cylinder l3 comprises a valve housing 3! provided with a valve seat 33 which divides the interior of the housing 3| into two chambers 35 and 31. The valve seat 33 is provided with a relatviely large valve opening 39 which connects the chambers 35 and 37 with one another when the valve 29 is open.

A valve member 4| is mounted in the valve housing 3| for movement to a closed position in engagement with the valve seat 33 to close the valve opening 39, and to an open position away from the valve seat to provide a substantially free communication of the chambers 35 and 31 with each other. The chambers 35 and 37 are continuously in communication with each other even when the valve member 4| is in closed position through a plurality of relatively small passages #33 formed in the valve member 6|. If desired, the passage 43 may be formed in the valve seat 33 instead of in the valve member 4!, as shown in Fig. 1.

The automatic valve 29 is connected in the fluid pressure conducting means 25 between the control valve 21 and the actuating cylinder IS with the valve chamber 35 communicating with the control valve 27, and with the valve chamber 3'! communicating with the actuating cylinder I3.

The movable valve member 4| is adapted to be moved to open position or to remain in the closed position when the control valve 2115 opened, in accordance with whether the breaker is operated under load or under no load conditions. For the purpose of operating the valve member 4| in this manner, the valve member 4| is carried by a relatively short rod 45 which extends into a bell shaped hollow body 41 disposed in the chamber 37. The hollow body 47 forms an actuating cylinder for the valve member 4|, and the body 51 is mounted centrally in the chamber 37 by means of a pair of struts 49 which extend inwardly from the walls of the valve housing 3|. The hollow body 41' and the struts A9 are preferably cast or formed integral with the valve housing 3|.

A valve controlling piston 5| is secured to the right-hand end of the rod 45, and the piston 5| is clamped by a washer 53 and a nut 55 to the central portion of an elastic membrane or diaphragm 51 which closes the open end of the hollow body 41 and which has its rim secured to the open edge of the body 4'! in any suitable manner as, for example, by a retaining ring 58 threaded on the end of the bodyll. A compression spring 59 is disposed in the hollow body 41 between the closed end of the body 41 and the valve actuating piston 5| for the purpose of biasing the valve member it! to closed position with a predetermined force. 7

The interior of the hollow body 4'! is in continuous communication with the air outside of the valve housing 3| through the agency of a passage 6| formed in a least one of the struts 49, so that the pressure within the hollow body 41 isalways the same as that of the outside air.

A slightly modified form of the automatic valve is shown in Fig. 2. The main elements of the valve shown in Fig. 2, with the exception of the valve housing, are identical in structure to the corresponding elements of the valve shown in Fig. l, and the corresponding identical parts are designated by the same reference characters. Since the main elements of the valve have already been described in detail in connection with Fig. 1 it is not deemed necessary to again describe these elements in connection with Fig. 2. The valve housing 63 in this modification of the invention is formed to provide an end closure or cover for the actuating cylinder |3. For this purpose, the housing 63 is provided with .a peripheral flange having substantially the same diameter as that of the cylinder |,3. The valve housing 63 is adapted to be secured to the end of the actuating cylinder is so that the valve housing serves as an end closure or cover for the cylinder I3, The struts 49 which support the hollow body 47, and the passage 6| therein are not shown in this figure since they extend in a direction perpe dicular to the plane of the drawing.

The operation of the automatic valve is briefly as follows. When the control valve 21 is opened to effect actuation of the circuit breaker, the medium under pressure, which in the present instance may be compressed air, flows from the source 23 through the control valve 27, the fluid pressure conductor 25, and through the passages 43 in the normally closed valve member 4| of the automatic valve 29 to the left-hand end of the actuating cylinder i3 and the fluid pressure moves the actuating piston i5 towards the right to effect closing of the circuit breaker. If at this time the circuit breaker is operated under 19 load conditions, th valve member 4| remains in losed D ition, as shown in Figs. 1 and 2 under the biasing action of the'spring 59, since the pressure in the chamber 31 does notbecome sufflciently high toeffect opening of the valve member; Under these conditions, the relatively small-passages 43 permit only a restricted flow of fluid to the actuating cylinder I3 so that the operating means and breaker are not operated at an excessively high speed during this no load operation of the circuit breaker. If the circuit breaker is operated under normal or full load conditions when the control valve 21 is opened, the fluid under pressure flows through the passages 43 in the closed valve member 4| to the actuating cylinder l3. Under these conditions of operation, the pressure in the actuating cylinder l3 and consequently in the chamber 31 of the automatic valve 29 rises rapidly and when the pressure reaches a predetermined value, it causes movement of the valve actuating piston towards the left in Fig, 1, or upwardly in Fig. 2 to eifect opening of the valve member 4|. When the valve member 4| is thus moved to open position, it provides for a substantially free flow" of the fluid under pressure through the relatively large valve opening 39 to the actuating cylinder |3 to effect actuation of the circuit breaker to closed position.

If the valve member 4| has been moved to open position, it remains in full open position irrespective of limited fluctuations in pressure within the chamber 31 even though the pressure falls a limited amount below the predetermined value. This results from the fact that a greater pressure or force is required to initiate opening of the valve than is required to maintain it in open position against the bias of the spring 59. This greater pressure or force is due partially to the air pressure in the chamber 35 acting against the back of the valve 4| over the area of contact between the valve and its seat when the valve is in closed position, partly to the suction effect of the fluid-tight seating of the valve against its seat, and partly to the fact that the interior of the hollow body 41 is in constant communication with the outside air so that no air pressure is built up in the interior of the body 41 by inward movement of the piston 5| and diaphragm 51 which would tend to assist the spring in closing the valve. Since the interior of the hollow body or cylinder 41 is always at atmospheric pressure and the air pressure in the chamber 31 is considerably above atmospheric pressure, slight or limited fluctuations in the air pressure in the chamber 31 will not produce oscillation of the valve 4|. The valve 4| once opened will thus remain in full open position until the control valve has been operated to shut off the air pressure. When the control valve 21 is closed, the valve member 4| is returned to its closed position by means of the biasing spring 59. If desired, a rubber bumper ring 61 may be provided in the hollow body to serve as an impulse damper for the valve actuating piston 5|.

Since the valve member 4| is always in closed position whenever the control valve is first opened, the relatively small passages 43 restrict the initial rush of fluid under pressure to the actuating cylinder l3 and thus to automatically damp the starting movement of the actuating piston l5.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made without departing from the spirit of the invention.

I claim as my invention:

1. In a fluid pressure operating means for a circuit breaker, an actuating cylinder, an actuating piston in said cylinder for actuating said breaker, a source. of fluid pressure for operating said piston, means connecting said source of fluid pressure to said cylinder, a control valve in said connecting means, and an automatic valve in said connecting means for controlling the flow of fluid to said cylinder in accordance with the magnitude of the load on said piston when said control valve is opened, said automatic valve comprising a valve housing having a pair of chambers separated by a valve member which is movable to open and to closed positions, one of said chambers communicating with said control valve and the other chamber communicating with said cylinder, said automatic valve having passages for continuously connecting said chambers to provide restricted flow of fluid to said cylinder when said control valve is opened even though said valve member is in closed position, spring means biasing said valve member to closed position, operating means in the chamber communicating with said cylinder operable in response to predetermined pressure conditions in the chamber to move said valve member to open position, said automatic valve having means for causing said valve member to remain in open position after it has been moved to open position irrespective of limited pressure fluctuations until said control valve is closed.

2. In a fluid pressure operating means for a circuit breaker, an actuating cylinder, an actuating piston in said cylinder for actuating said breaker, a source of fluid pressure for operating said piston, means connecting said source of fluid pressure to said cylinder, a control valve in said connecting means, and an automatic valve in said connecting means for controlling the flow of fluid to said cylinder in accordance with the magnitude of the load on said piston when said control valve is opened, said automatic valve comprising a valve housing having a pair of chambers separated by a valve member which is movable to open and to closed position, one of said chambers communicating with said control valve and the other chamber communicating with said actuating cylinder, said automatic valve having passages for continuously connecting said chambers to permit restricted flow of fluid to said actuating cylinder when said control valve is opened even though said valve member is in closed position, spring means biasing said valve member to closed position, and valve operating means separate from said valve member and connected thereto disposed in the valve chamber which communicates with the actuating cylinder for moving said valve member to open position when the pressure in said chamber communicating with the actuating cylinder exceeds a predetermined value.

3. In a fluid pressure operating means, an actuating cylinder, an actuating piston in said cylinder, a source of fluid pressure for operating said piston, means connecting said source of fluid pressure to said cylinder, a control valve in said connecting means, and an automatic valve in said connecting means for controlling the flow of fluid to said cylinder in accordance with the magnitude of the load on said piston when said control valve is opened, said automatic valve comprising a valve housing having a pair of chambers separated by a valve member which is movable to open and to closed position, one of said chambers communicating with said control valve and the other chamber communicating with said actuating cylinder, said automatic valve having passages which continuously connect said chambers with each other to permit restricted flow of fluid to' said actuating cylinder when said control valve is opened even though said valve member is in closed position, spring means biasing said valve member to closed position with a predetermined :force, a hollow body forming a valve operating cylinder disposed in the chamber which communicates with said actuating cylinder, a valve operating piston movable in said hollow body and connected to said valve member for moving said valve member to open position when the pressure in said chamber which communicates with :said actuating cylinder exceeds a predetermined value, said hollow body being mounted on spaced struts extending inwardly from the walls of said valve housing, and at least one of said struts having a passage which connects the interior of said hollow body with the outside air.

4. In a'fluid pressure operating means, an actuating cylinder, an actuating piston in said cylinder, a source of fluid pressure for operating said piston, means connecting said source of fluid pressure to said cylinder, a control valve in said connecting means, and an automatic valve in said connecting means for controlling the flow of fluid to saidcylinder in accordance with the magnitude I of the load on said piston when said control valve is opened, said automatic valve comprising a valve housing having a pair of chambers separated by a valve member which is movable to open and to closedposition one'of-said chambers communicating with said control valve and the other chamber communicating with said actuating cylinder, said automatic valve having passages which continuously connect said chambers with each other to permit restricted flow of fluid to said actuating cylinder when said control valve is opened even though said valve member is in closed position, spring means biasing said valve member to closed position with a predetermined force, a hollow body forming a valve operating cylinder disposed in the chamber which communicates with said actuating cylinder, a valve operating piston movable in said hollow body and connected to said valve member for moving said valve member to open position when the pressure in said chamber which communicates with said actuating :Cylinder exceeds a predetermined value, said valve operating piston being secured to an elastic membrane covering the open-end of said hollow body.

5,. In a fluid pressure operating means for a circuit breaker, an actuating cylinder, an actuating piston in said cylinder for actuating said breaker, a source of fluid pressure for operating said piston,means-connecting said source of fluid pressure to said cylinder, a control valve in said connecting means, and an automatic valve in said connecting means for controlling the flow of fluid to said cylinder in accordance with the magnitude of the loadon said piston when said control valve is opened, said automatic valve comprising a valve housing having a pair of chambers separated by'a valve member which is movable to open and to closed position, one of said chambers communicating with said control valve and the other chamber communicating with said actuating cylinder, said automatic valve having passages which continuously connect said chambers with each other to permit restricted flow of fluid to said actuating cylinder when saidcontrol valve is opened even though said valve member is in closed position, spring means biasing said valve member to closed position with a predetermined force, a hollow body forming a valve operating cylinder disposed in the chamber which communicates with said actuating cylinder, a

valve operating piston movable in said hollow body and connected to said valve member for moving said valve member to open position when the pressure in said chamber which communicates with said actuating cylinder exceeds a predetermined value, and means connecting the interior of said hollow body with the outside air.

6. In a fluid pressure operating means for a circuit breaker, an actuating cylinder, an actuating piston in said cylinder for actuating said breaker, a source of fluid pressure for operating said piston, means connecting said source of fluid pressure to said cylinder, a control valve in said connecting means, and an automatic valve in said connecting means for controlling the flow of fluid to said cylinder in accordance with the magnitude of the load on said piston when said control valve is opened, said automatic valve comprising a valve housing having a pair of chambers separated by a valve member which is movable to open and to closed position, one of said chambers communicating with said control valve-and the other chamber communicating with said actuating cylinder, said automatic valve having at least one passage which continuously connects the chambers to permit restricted flow of fluid to said actuating cylinder when said control valve is opened even the said valve member is in closed position, spring means biasing said valve member to closed position, a hollow open ended bodydisposed in the chamber which communicates with the actuating cylinder, a diaphragm closing the open end of said body and means connecting said diaphragm to said valve member for moving said valve member to open position when the pressure in said chamber communicating with said actuating cylinder exceeds a predetermined value.

7. In a fluid pressure operating means for a circuit breaker, an actuating cylinder, an actuating piston in said cylinder for actuating said breaker, a source of fluid pressure for operating said piston, means including a control valve for connecting said source of fluid pressure to said cylinder, and an automatic valve for controlling the flow of fluid to said cylinder in accordance with the load conditions on said piston when said control valve is opened, said automatic valve comprising a valve housing on the end of said actuating cylinder forming a closure for the end of said cylinder, said valve housing having a pair of chambers separated by a movable valve member, one of said chambers communicating with said control valve and the other chamber com- *municating with said actuating cylinder, said automatic valve having passages for permitting restricted flow of fluid to said cylinder when said r control valve is opened and said valve member is in closed position, and having separate actuating means connected to said valve member and disposed in the valve chamber communicating with said cylinder for causing movement of said valve member to open position when the pressure in said cylinder exceeds a predetermined value.

8. In a fluid pressure operating means for a circuit break r, an actuating cylinder, an actuating piston in said cylinder for actuating said breaker, a source of fluid pressure for operating said piston, 1116-3215 connecting said source of fluid pressure to said cylinder, a control valve in said connecting means, and an automatic valve in said connectingmeans for controlling the flow of fluid to'said cylinder in accordance with the magnitude of theload onsaid piston, said automatic valve having a closed position in which .it

cylinder and when opened permitting an increased flow of fluid to said cylinder, and separate actuating means connected to said valve and disposed in the valve chamber which com- 5 municates with said cylinder for causing opening of said valve member When the pressure in said cylinder exceeds a predetermined value.

ALFRED LOOS.

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