US2454189A - Fluid pressure operated circuit interrupter - Google Patents

Description

Nov. 16, 1948. 5, 55 2,454,189

FLUID PRESSURE OfERATED CIRCUIT INTERRUPTER Filed Jan. 12. 1946 WITNESSES: INVENTOR Gerhard [604765. BY W 4 AIZTORINEY Patented Nov. 16,1948

FLUID PRESSURE OPERATED CIRCUIT INTERRUPTER Gerhard Lenties, Pittsburgh, Pa assignor to Westinghouse Electric Corporation, East Pittsburgh, Pm, a corporation of Pennsylvania Application January 12, 1946, Serial No. 640,838

7 Claims. (Cl. 200-82) may be equipped with a heavy spring for effecting rapid opening of the contact elements, and a piston subject to compressed air for closing the contact elements, the completed assembly being preferably capable of eilecting an open-closeopen operation within a time interval of less than 1'7 cycles for certain classes of 60 cycle service. Because of the power and speed of operation thus required for a circuit breaker of this class, it is desirable to provide an operating mechanism having maximum simplicity and ruggedness of de-' sign, but nevertheless adapted for smooth and relatively shock-free operation.

In the construction of a circuit breaker oi the above type, in order to prevent development of excessive shock and vibration during operation of the powerful actuating piston, it has been proposed to control the supply of compressed air in such a manner as to insure relatively smooth and safe acceleration of the piston, particularly during initial movement. For this purpose there has been provided a control valve means functioning to restrict or reduce the rate of supply of compressed air to the piston cylinder during initial movement of the piston, and designed to move quickly from a throttling position to an open position for permitting quick final buildup in pressure, following a predetermined initial movement of the piston, preferably at the start of compression of the accelerating spring or other load such as at the point in its traverse corresponding to the initial touching of the contact elements of the circuit breaker. In this way, the piston is prevented from acquiring such a velocity as might result in undesired slamming during operation of the circuit breaker, while full operating force becomes available for overcoming any resistance to final closing of the breaker contact elements. In the co-pending application of James M. Cumming, filed April 21, 1945, Serial Number 589,581, now Patent Number 2,434,549,

disclosed a circuit breaker having a control valve means embodying a positive latch for holding the control valve means in its throttling position against the force of a spring, together with means for releasing the latch at the proper time, including a plurality of interlocking levers.

It is the object of my invention to provide a new and improved control or throttle valve mechanism of the above type, in which rugged and simple features of construction arecombined to promote positive operation and to minimize the effect of friction on the speed of operation of the mechanism.

Another object of the invention is to provide an improved throttle valve mechanism embodying a minimum number of operating parts, thus facilitating installation of the mechanism in a circuit breaker equipment of existing design.

Other objects and advantages of the invention will appear in the following more detailed description thereof, taken in connection with the accompanying drawings in which:

Figure 1 is a diagrammatic view, partly in section, of the operating portions of a fluid pressure operated circuit breaker equipment having associated therewith a preferred form of control valve mechanism constructed in accordance with the invention; 4

Fig. 2 is a fragmentary sectional view taken partly on the line II II of Fig. 3 of the control valve mechanism shown in a closed position corresponding to the open position of the circuit breaker; and

Fig. 3 is a sectional view taken substantially along the line IIIIII of Fig. 2.

Referring to the drawing, in Fig. 1 there is illustrated in diagrammatic form a portion of a single pole unit of a fluid-pressure-operated circuit breaker, comprising a suitable frame structure (not shown) supporting stationary contact elements 5 in the power circuit to be controlled, a movable resilient contact element 8 cooperative therewith and secured to a rod I, a cylinder I0 having mounted therein an operating piston II, and a piston rod l2, the upper end l3 of which is pivotally connected to the rod 1 through the medium of a beam [4 fulcrumed on a stationary pin I5. A coil spring I! is mounted in cooperative relationship with the movable contact element 6 for urging that element toward an open circuit position. The piston II is responsive to the pressure of air admitted to a pressure chamber 20 for actuating the piston rod l2, beam i4 and rod 1 to move the contact element 6 into granted J nu y 1 43, I 1 e mple; there is circuit closing engagement with the stationary contact elements 5, in opposition to the force exerted by opening spring ii and resilient contact element 3.

For maintaining the circuit breaker elements Just described in circuit closing position, the circuit breaker apparatus is further provided with a transversely disposed beam 22, one end of which is Journaled on a pin 23 carried by a link 24 that is in turn pivotally connected to a pin 25 carried The latch mechanism 3i may be of any suitable design and, as illustrated, com-prises a main latch member 32 Journaled on a stationary pin 33 secured to the frame structure, a release pawl 34 pivotally connected to the frame structure by means of a pin 35 for cooperation with the latch member 32, and an auxiliary latch member 36 adapted for cooperation with the pawl 34. The main latch member 32 has a surface 38 adapted for latching engagement with the roller 30, and an extension 40 adapted for interlocking engagement with a portion of the pawl 34 for resisting clockwise movement of-the main latch member about pin 33 under the force tending to raise the end of the beam 22 carrying the roller, and thus ending to effect disengagement of the latch member 32 from the roller. For biasing the main latch member 32 in a counter-clockwise direction, there is provided a spring 42, which is interposed between a suitable lug on the frame structure and the head of a link pivoted to the latch member.

-For tripping the latch mechanism 39, there is provided a trip coil 44, which is adapted to be energized through the medium of a suitable trip control circuit (not shown) for causing upward movement of an armature carrying a plunger that is operatively aligned with a portion of the pawl 34. The pawl 34 is normally urged into the position shown in Fig. l by means of a spring 4i, which is adapted to yield upon operation of the pawl by the trip plunger 45. The auxiliary latbh member 36 is inoperative when the parts are positioned as shown in Fig. l, but serves to hold the pawl 34 out of interfering engagement with latch member 32 when the beam 22 and other operating elements of the circuit breaker are in circuit opening position. A coil spring 49 is interposed between a portion of the cylinder structure i I and a lug 53 on the auxiliary latch 36, and acts to tilt the latter in a clockwise direction about pin 35, causing the lug Bill to carry the pawl iii in the same direction; when the end of the beam 22 carrying roller 3a is swung upwardly during a circuit breaker opening operation. It will be noted that a lug 5i carried on the upper end of auxiliary latch 35 is adapted to be engaged by the free end of the beam 23, when that beam is moved to the circuit closing position as shown in Fig. 1. With the auxiliary latch member 35 thus held down, the spring ii is permitted to maintain the pawl 34 in interlocking engagement with the main latch member 33.

For controlling the supply of fluid under pressure to the chamber 23, there is provided a magnet valve assembly, generally indicated at 55, comprising a casing having a valve chamber 56 iii communicating with a fluid supply pipe 31, which may be connected to any suitable source of fluid under pressure. Within chamber 56 is mounted an inlet valve 58 for controlling communication from the valve chamber to a passageway 60 leading to the pressure chamber 20. The supply valve 58 is normally urged toward a seated position by a coil spring 82 mounted in the valve chamber 56, and is provided with a valve stem 33 which extends upwardiy and terminates in an armature portion (not shown) movably disposed within a magnet coil carried by the frame structure. The magnet coil 85 is adapted to be energized through the medium of a suitable control circult (not shown) which may be arranged in any a proved and well known manner for insuring the desired automatic operation of the circuit breaker equipment. The valve stem 63 also carries a discharge valve element 61 which is operative to vent the passagway 60 to atmosphere when the supply valve element 58 is in its seated position, as shown in Fig. 1. Upon energization of the. magnet coil 65, the stem 63 is shifted downwardly to close the valve element 61 while opening the supply valve 58 to effect supply of fluid under pressure to the pressure chamber 20 above the piston ii. i

It is not deemed necessary to illustrate the control circuits for the magnet coils 44 and 65, but it will be understood that any suitable circuit breaker controlling system may be provided to furnish theusual features of automatic operation well known in the circuit breaker art. For example, the trip coil 44 may be arranged for energization in response to development of a fault in the main circuit controlled by the circuit breaker, or alternatively to be subject to manual control. If the circuit breaker equipment includes means for effecting a quick automatic reclosing operation following an opening operation in response to a fault, the circuit for energizing the magnet coil 85 may be arranged to initiate energization thereof instantaneously upon tripping of the circuit breaker apparatus or soon thereafter, to thus insure a subsequent reclosing operation with minimum loss of time.

According to the invention, a throttle valve assembly, indicated generally by the reference character I0, is provided for controlling the rate of supply of fluid under pressure through the passageway 60 to the piston chamber 20 at a rate determined in accordance with the operation of the circuit breaker. The throttle valve assembly includes a casing portion ii carried on the cylinder i0, and having a suitable bore 13 disposed substantially vertically and in intersecting relation with respect to a passage'iia communicating through a pipe H with the passageway 60. As shown diagrammatically in Fig. 3, passageway 16 extends through the casing section 6i and wall of cylinder ill to the piston chamber 20. A restricted bypass i4 is formed in the casing section ii, as is best shown in Fig. 3, for permitting flow of fluid around the bore 13 at a rate determined "by adjustment of a screw-threaded valve elementid. Slidably mounted in the vertical bore i3 is a valve element i8, which is urged downwardly under the force or a coil spring 19 that is interposed between the lower end of the valve element and a cap carried by the casing section ii and secured thereto by suitable means, such as bolts 32. With the valve element 18 held in its lowermost position, as shown in Fig. l, the passageway 13 is maintained open so that flow of fluid under pressure is virtually unrestricted.

n the other hand, when the valve clement id is shifted to its uppermost position, ee is best shown in Fig. 2, flow oi fluid under pressure is li-mltedto the flow area of the bypass The throttle valve clement i8 is arranged ior operation in accordance with operation of the piston rod 12 and associated elements of the circult breaker. For this purpose the valve element is has secured thereto a stem which extends upwardly through the bore l3 and through a suitably packed aperture in the cap member 80, the upper end of the stern carrying a clevis member iii. The parallel walls oi clevis member 9! are apertured to receive a pin us to which is pivotally connected-a movable, substantially vertically aligned latch member so. The latch member all a lug 96 disposed thereon just below a sloping cam surface 96, which is adapted to be urged into engagement with a roller 3? iournaled on a pin {f3 carried by pair of upwardly extending arm portions lull of the cap members so. Univ one 02 the portions Mill is illustrated in the sectional views included in the drawing. A small pring is interposed between an upper flat surface oi the olevis member 5i and a lower corner suriace of latch member 95 for biasing the latch member toward the roller Si. also operatively aligned with the cam surface 56 of the latch member is an extension of the pin 28 which, as already explained, operatlvely connects the beam 22 to the piston rod 52.

For providing a lost motion connection be= tween the clevis member 9i and the beam 22 of the circuit breaker mechanism, there is provided a bifurcated link member generally indicated by reference character till, which preferably comprises spaced parallel portions, joined at the upper and lower ends, only one .02. these portions being represented in the drawing. The lower end of the linlr member lid is pivotaliy connected to the pin 92, between the spaced portions of clevis member ill. The link member has formed therein an elongated slot into which both the end of pin 253 and the roller 98 are adapted to extend, as indicated in Fig. l of the drawing. Mounted on the uppermost end of the link member lid is a set screw lid which may be adjusted and locked in place by means oi a lock nut H6, to provide means for limiting the traverse within the slot H2 or the pin 23 carried by beam 22. When the bear 2:. is tilted to the open position oi the circuit breaker, as indicated in Fig. 2, the pin 23 engages the end of the set screw H5 to lift the link member till, stem 90 and valve element iii.

In operation, it the circuit breaker equipment is disposed in its circuit closing position, as shown in Fig. 1, the beam 22 is held in a substantially horizontal position with the roller 30 in latching engagement with the main latch member 32, so that the circuit breaker is held positively in the circuit closing position against any force tending to open the contact elements 5 and 5. At the same time the spring 19 is offective to hold the throttle valve element IS in its lower or open position, as shown in Fig. 1, while the latch member 94 is also disposed in its lowermost or unlatched position, with the lug 96 thereof located beneath the roller 9?.

If it is desired to efiect an opening operation or the circuit breaker, the magnet coil 54 is energized through the medium or the usual controlling circuit, as already explained, whereupon the plunger 45 is quickly raised to disengage the pawl M from the main latch member as. Due

to the relatively small area oi contact between the inclined suriace oi the main latch moms her and the roller 89, the spring 32 is unable to resist the slight clockwise movement of the latch required to release the beam 22 and the latter is consequently moved upwardly about pin 223, while rod ii, beam i i, and rod a are at the some time actuated by the spring ill to effect disengagement of the contact element from the contact elements The piston ii is carried upwardly during the upward movement of the piston rod i2 but it the circuit breaker is equipped for a quick automatic recioslng operation, the operation or the usual auxiliary reciosing means (not shown) re" sults in energlzatlon oi the magnet coil liii in time to operate th supply valve for admitting compressed air to the piston chamber 2b before piston it has reached its uppermost position. Upon the resultant supply of compressed air to chamber 2d, the upward motion of the piston M will thus be reversed prior to any engagement between pin and to the set screw i to mounted on the upper end oi the slotted linlr member no. The throttle valve element "it thus remains in its full open position to insure sub stantially unrestricted flow of compressed air through passageway to, pipe ii, and passageway to pressure chamber 2Q, to furnish the maximum force needed for reversing the movement of the mechanism and causing quick reclosure of the circuit breaker.

If the fault in the'controlled circuit has not been removed at the time when the reclosure of the circuit breaker occurs, the trip coil ill will agalns be energized and coil t5 will be deenergized for venting the piston chamber 28 to atmosphere, thereby rendering spring ll again operative to open the circuit breaker. It will be understood that suitable dump valve means may be provided for augmenting the discharge of compressed air from piston chamber 2b in order to promote quick upward movement of piston ll. One form of such dump valve and a suitable control circuit for the complete mechanism is shown in Patent No. 2,361,178, issued October 24, 1944 to James M. Cumming, and assigned to the assignee of the present application. For the purpose of disclosing the present invention, however, it is deemed unnecessary to show such a dump valve and control circuit in the drawing.

Assuming that the circuit breaker is moved to its circuit opening position with the contact element 6 held out of engagement with contact elements 5 under the force of spring ll, it will be apparent that the beam 22 will be moved to the position illustrated in Fig. 2 of the drawing. At this time, the operating piston Ii will be moved to its uppermost position within cylinder it, while the pin 28 carried by the piston rod l2 and beam 22 will be carried into engagement with the set screw M5 for raising the link llii, stem 60 and valve element iii to the throttlingposition as illustrated in Fig. 2. As the latch. 9c is at the same time carried upwardly, the lug E35 thereof is caused to rideover the roller Q7 and then to engage that element under the force exerted by spring Hi2, so that the valve element '58 will then be latched in its upper or throttling position to limit the communication between the passageway Gil and piston chamber 20 to the how area of the bypass it. 11

If the controlling circuit for the circuit brea i is now energized in the usual manner tofcause acccneo a closing operation, the consequent energizatio'n oi the magnet coil 85 of the magnet valve device 55 eifects unseating oi the supply valve element 58 against the iorce of spring 82, while discharge valve 81 is moved to its seated position. Compressed air is then supplied from the usual source by way oi? pipe 51, valve chamber 56, past the unseated valve element 58, thence through passageway to, pipe i1 and restricted bypass 14 to the piston chamber 20. The piston ii is thereby moved downwardly by the pressure of air for operating the rod l2, beam i4 and rod '5 tobring the movable contact element 6 toward the contact elements l5.

It will be understood that although suillcient compressed air is quickly supplied by way of the communication Just described, including the restricted bypass IQ, to effect prompt closing movement or the associated circuit breaker operatin elements, the increase of pressure or fluid in chamber it] is nevertheless so controlled as to prevent the piston i i and other movable elements from acquiring an excessive velocity during the initial operation. As the piston it continues its downward movement, the pin 28 carried by piston rod it engages the cam surface 86 of latch mem= her at and for es the latter to the left, as viewed in Fig. 1, so that the lug 9b is released from the roller ill. The spring lid is thereby rendered efiective to shift the assembled valve element l9, stem til, latch member so and linlr member lib downwardly. The exact point at which th pin 22 releases the spring-pressed valve element lit may be varied somewhat by proper adjustment of the stem ilil with respect to the valve element it. it being observed that a, loci: nut 11% is attached to the lower threaded end or the stem for fixing these elements in the desired position.

With the valve element it] thus shifted to its open position substantially instantaneously, the supply of compressed air to the piston chamber is continued at a suddenly increased rate of flow, and the air pressure in chamber Ed is thus increased quickly so that sufficient force is exerted on the piston ii to effect final movement thereof to the fully closed position of the circuit breaker, regardless of any increase in resistance to such movement that might be caused during final closing operations oi the contact elements 6: and

From the foregoing it will be seen that an improved control valve mechanism constructed in accordance with my invention may be assembled from a minimum number of sturdy yet inexpensive operating elements, which are adapted to operate smoothly and without substantial variation in speed due to friction or other cause. The control valve assembly is readily accessible for inspection or repairs, and may easily be adjusted to insure its operation at the desired instant in the cycle of operation of the circuit breaker mechanism.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a fluid pressure operated circuit breaker having relatively movable contact means, a cylinder, piston means operative upon an increase in fluid pressure in said cylinder for moving said contact means to a circuit closed position, and means for moving said contact means to an open circuit position, the combination of supply valve means operative to supply fluid under pressure through a communication to said cylinder, throttle valve means interposed in said communicaticn and having an element movable between a position for restricting i'iow therethrough and an open position for permitting maximum flow, means for biasing said movable throttle valve element toward own position, a positive latch pivotally mounted on said movable throttle valve element and engageable with a fixed part for releasably holding said throttle valve element in the restricting position, a member movable by said piston means for moving said throttle valve element against its bias, and said member angaging and releasing said latch during movement of said piston means prior to movement or said throttle valve element.

2. In a fluid pressure operated circuit breaker having relatively movable contact means, a cylinder. and movable abutment means operative upon an increase in fluid pressure in said cylinder for moving said contact means, the combination of supply valve means operative to supply fluid under pressure through a communication to said cylinder, throttle valve means interposed in said communication having a position ior restricting flow therethrough and an open position for permitting maximum flow, means for biasing said throttle valve means toward one position, a positive latch ior holding said throttle valve means in the other position, a pin and slot lost motion connection between said movable abutment means and said-throttle valve means for moving said throttle valve means against said biasing means to locked position when the pin engages one end oi the slot, and said pin engaging said latch before reaching the other end of the slot for releasing said latch prior to any movement of the throttle valve means toward said one position.

3. In a fluid pressure operated circuit breaker having relatively movable contact means, operating mechanism including a cylinder, a piston operative upon an increase in fluid pressure in said cylinder for moving said contact means to a circuit closed position, and means for moving said contact means to an open circuit position, the combination of supply valve means operative to supply fluid under pressure through a communication to said cylinder, throttle valve means interposed in said communication having a position for restricting flow therethrough and an open position for permitting maximum flow, means for biasing said throttle valve means toward open position, a latch element movable with said throttle valve means and also movable relative thereto, a stationary element engageable by said latch element for releasably holding said throttle valve means in the restricting position, and a link. member connected to actuate said throttle valve means and having lost motion cooperation with a movable part of the operating mechanism, and said movable part of the operating mechanism engaging and moving said latch to unlatched position upon predetermined movement of said contact means toward the closed circuit position.

4. A fluid pressure operated circuit breaker having contact means movable to open circuit position and to closed circuit position, an operating cylinder, a piston operative upon supply 01' fluid under pressure to said cylinder for moving said contact means, fluid pressure control means including a passage for supplying fluid under pressure to said cylinder, valve means biased toward one position and movable to another position to control the rate of flow of fluid under pressure through said passage, a latch pivotally connected to said valve means for at times locking same in said other position against the bias thereon, a link pivotally connected to said valve means at the pivot of said latch and being movable in response to movement of said contact of fluid under pressure to said cylinder for moving said contact means, fluid pressure control means including a passage for supplying fluid under pressure to said cylinder, valve means biased toward an open position and movable to a throttling position to control the flow of fluid under pressure through said passage, a latch operative to hold said valve means in throttling position and having a cam surface thereon, a link having a lost motion connection with said piston for shifting said valve means .to throttling position so as initially to reduce the rate of supply of fluid under pressure to said cylinder during subsequent movement of said contact means from the open circuit position, and an element movable with said piston along said link to engage the cam surface and release said latch after said piston has been moved through a predetermined portion of a circuit closing stroke.

6. A fluid pressure operated circuit breaker having contact means movable to open circuit position and to closed circuit position, an operating cylinder, a piston operative upon supply of fluid under pressure to said cylinder for moving said contact means to closed circuit position, a member operative with said piston, spring means operative to move said contact means to open circuit position, fluid pressure control means including a passage for supplying fluid under pressure to said cylinder, a valve biased toward an open position and movable to a throttling position to control the flow of fluid under pressure through said passage, an elementmounted on said cylinder, 9. positive latch releasable by said member and cooperative with said element for at times holding said valve in throttling position.

10 and connected to said valve tor shifting it to the throttling position to reduce the rate of flow of fluid under pressure to said cylinder during initial movement of said contact means from the closed circuit position, said link means having a slot receiving said member and constituting a lost-motion connection between said member and said valve, and said member in the slot engaging said latch near one end of the slot so that said piston must almost complete a contact closing stroke prior to effecting operation of said latch to released position.

7. In a fluid pressure operative circuit breaker of the type including movable contact means, means for moving said contact means to an open circuit position, a movable abutment operative upon an increase in the pressure 01' fluid in a chamber for moving siad contact means to a closed circuit position, and supply valve means operative to supply fluid under pressure to said chamber, the combination therewith oi throttle valve means interposed between said supply valve means and said chamber, said throttle valvemeans including a spring and a movable valve element biased by said spring toward an open position for permitting supply of fluid to said chamber at a maximum rate, a latch pivotally connected to said movable valve element, stationary means engageable with said latch for releasably holding said throttle valve means in a throttling position to reduce the rate at which fluid under pressure can be supplied to said chamber, link means having a lost-motion operative relation to said movable abutment for efiecting movement of said valve element to the throttling position only when said abutment is shifted to a position corresponding to the open circuit position of the contact means, and means operative with said movable abutment to engage and release said latch upon a predetermined movement of said abutment for closing said contact means.

GERHARD LENTJES.

REFERENCES CITED The following references are .of record in the flle of this patent: c

UNITED STATES PATENTS Name Number Date and link means cooperative with said member 0 3,3 1 Cumming at a], Sept, 13, 1945

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