US2431222A - Circuit breaker - Google Patents

Description

Nov. 1s, 1947. B, P, BAKER 2,431,222

CIRCUIT BREAKEB Filed Feb. 24, 1945 Patented Nov. 18, lit-947 UNITED STATES lATENT OFFICE CHRCUET BREAKER Benjamin P. Baker, rEurtle Creek, Pa., assigner to Westinghouse Electric Corporation, East l Claims. l

This invention relates to circuit breaker mechanisms, and more particularly to a uid pressure operated motor designed for rapidoperation of relatively heavy apparatus.

It has been proposed to provide iiuid pressure responsive apparatus for actuating heavy circuit breakers which must be accelerated at rapid speeds when moved from one position to another and must at the same time be protected from violent shocks during operation. In order to render a circuit breaker apparatus of this type o-perative at the desired speed without being subjected to unduly heavy vibration, it is necessary to equip such apparatus with shock absorbing means. It is further desirable to provide an auxiliary means for exerting an accelerating force at least during the beginning oi an operating stroke of a circuit breaker actuating motor.

One object oi my invention is the 'provision of an improved fluid pressure motor which may be employed for actuating a heavy mechanism at high speed, and which includes improved means for arresting motion of the apparatus at the end of each stroke.

Another object of my invention is the provision of a duid pressure motor comprising a cylinder and an operating piston and fluid pressure means conditioned by fluid under pressure supplied for actuating the piston to eiect smooth deceleration of the piston as it approaches the end of an operating stroke.

t is a further object of my invention to provide a iluid pressure motor of the class just described in which the uid pressure responsive shock absorbing means is conditioned by fluid supplied to the cylinder for exerting an initial accelerating force to the piston at the beginning of a return stroke.

Still another object of the invention is to provide an improved liuid pressure responsive operating mechanism for a circuit breaker having associated therewith a combination shock absorbing and accelerating device, including a movable abutment subject to the pressure of iiuid supplied for operating the mechanism and adapted for engagement by the operating piston of the circuit breaker, and means for controlling the pressure of fluid to which the movable abutment is subjected.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, both as to structure and operation together with additional objects and advantages thereof, will be best understood from the following detailed descripton of several embodiments thereof when read in conjunction with the accompanying drawing, in which: the single figure is an elevational sectional view of a portion of a iiuid pressure operated circuit breaker mechanism constructed in accordance With the invention.

Referring to the drawing, there is illustrated an operating mechanism for a circuit breaker including a cylinder casting l having a base portion which is adapted to be supported on a suitable insulating structure, not shown, and which is arranged to carry an arc-extinguishing structure of insulating material, not shown. The parts of the complete circuit breaker which are not shown herein are as disclosed in L. R. Ludwig et al. Patent No. 2,342,809 issued February 29, 1944, to the assignee of this invention. The cylinder casting l is adapted to house a fluid pressure actuating means for operating the circuit breaker, the essential elements of which are shown in fragmentary form as comprising a stationary contact member .2 of tubular construction supported in the upper portion of the circuit breaker, and a movable contact element 3 adapted to be moved upwardly into tlelescoping engagement with `the stationary Contact element at one time, and downwardly and out of contact with the stationary element for interrupting the circuit at another time. For operating the movable contact element 3, there is provided a piston 4 which is slidably mounted in a bore formed in the cylinder casting l, forming at one side thereof a piston chamber 5 communicating with an inlet passage 6, and at the opposite side of the piston a piston chamber 'l which communicates with a passage 8 by way of a port 9 formed in the wall of the chamber. In the present embodiment of the invention, the piston 4 is adapted to engage a shock absorber l0 mounted at the upper end of the cylinder casting, which shock absorber may comprise a plurality of resilient rings formed of rubber or the like.

According to the invention, a combination pneumatic shock absorber and accelerating device, generally indicated by the reference character i2, is provided at the lower end of the cylinder casting I and comprises a casing section i3, which may be secured to the cylinder casting by any suitable means such as bolts, not shown, and which has formed therein a pressure chamber I4 communicating with the lower end of the piston chamber 1 formed in the casting. The casing section I3 is provided with a centrally disposed cylinder portion I5 which is arranged coaxially of the piston chamber 1 and which has mounted therein a movable abutment or piston element I1, the upper surface of which is adapted to seat on the lower end of the wall of the piston chamber 1, as shown in the drawing. If desired, a light spring I8 may be interposed between the movable abutment I1 and the lower wall of the chamber I4 for yieldingly maintaining the abutment in the normal position as illustrated.

The pressure chamber I4 or the shock absorbing device I2 communicates with a conduit 20 leading to a conduit 2 I, through which fluid under pressure may be supplied both to the passage E and to the chamber I4 by a control valve device hereinafter described. For preventing back flow of fluid under pressure from the chamber I4 to the conduit 23, there is provided a ball check valve 22, which is held in engagement with a suitable seat formed in the casing section I3 under the pressure exerted by coil spring 23 which is interposed between the ball check valve and the lower wall of the casing section. The pressure chamber I4 also communicates with the passage 8 formed in the cylinder casting through the medium of a conduit 25 and a conduit 26 leading from the supply valve device, as hereinafter described. A ball check valve 21 is mounted within the chamber I4 for preventing backflow of fluid under pressure from that chamber to the conduit 25, the valve being urged into engagement with a suitable seat under the force of a coil spring 28. In order to limit the maximum pressure of fluid in the pressure chamber I4, there is provided a control valve element 3D which is disposed in a valve chamber 3| formed in a valve portion 32 carried by a bottom element of the casing section I3. This valve `element 30 is normally held in engagement with a seat 34 under the force of a coil spring 35 mounted in the valve portion 32, and controls communication between the pressure chamber I4 and an exhaust passage 3S, which is formed in an adjustable member 31 having screw-threaded engagement with the casing portion -32 for permitting regulation of the force of the spring 35.

For 4controlling the release of fluid under pressure from the chamber at one side of the piston 4 when uid pressure is applied to the opposite side, there is provided a valve device generally indicated by the reference character 38, which comprises an upper casing section 39 suitably mounted on a bolting race 43 of the cylinder casting I, and a similarly formed casing section 4l secured to a bolting face 42 of the casting. Formed in the casing section 39 is a vertically disposed bore 43 which communicates with a supply Ypipe 44 connected to a suitable source of supply of fluid under pressure, not shown. The bore v43 also communicates with a port 45 connected to the pipe or conduit 2l, and with an atmospheric exhaust port 46.

Interposed in the supply pipe 44 is a magnet valve device 41, which may comprise a normally closed valve 41a operative upon energiza'tion of a suitable magnet coil 41h through the medium of a control circuit (not shown) to cause fluid under pressure to be supplied through pipe 44 to the bore 43.

The lower casing section 4l also has formed therein a vertically disposed bore 48 which communicates with a supply pipe 49 leading to the same source of supply as does the pipe 44. An atmospheric exhaust port 5I and a fluid supply port 52 communicating with conduit 25 are formed in the casing section 4l in communication with the vertically disposed bore 48. It will be noted that the bores 43 and 48 are aligned coaxially. A magnet valve device 59 is interposed in the supply pipe 43 for controlling the supply of fluid under pressure to the bore 48. This device may have a construction similar to that of the magnet valve device 41, and is likewise operable upon energization of a suitable control circuit (not shown) to initiate the supply of fluid under pressure to the bore 43.

Operatively mounted in the vertically disposed b'ores 43 and 48 of the casing sections 39 and 4I is a valve unit having a stem 55, to the upper end of which is adjustably secured a valve portion 56 slidably mounted in the bore 43, and to the lower end of which is similarly secured a valve portion 51, which is slidably disposed in the bore 48. The stem 55 thus extends between the casing sections 33 and 4I and slides through a sleeve El loosely disposed between the two casing sections. One of a pair or washers G2 is interposed between each end of the sleeve 5I and the adjacent casing section for engagement with a coil spring 64 which encircles the sleeve El and serves to limit upward and downward movement of the stern and upper and lower valve elements 59 and 51. The stem 55 and valve elements 55 and 51 are so proportioned that upon movement of the assembly to its uppermost position, as shown in the drawing, the upper valve element 55 will cut off communication between the supply pipe 44 and the port 45 while establishing communication from the conduit 2| to the exhaust port 46. At the same time, the lower valve element 51 is positioned to close the exhaust port 5I and to establish communication from the supply pipe 49 through the port 52 to the conduit 26. It will be understood that upon supply of iluid under pressure to the upper supply pipe 44, as hereinafter explained, the valve assembly will be moved downwardly under the force of pressure applied to the upper valve element 5S, until that element establishes communication between the supply pipe 44 and the port 45 and closes the exhaust port 48, while the valve element 51 cuts olf communication between the pipe 49 and port 52 and connects the conduit 26 to the atmospheric eX- haust port 5I. It will, of course, be understood that the magnet valve devices 41 and 53 are provided for selectively controlling the supply of fluid under pressure through one or the other of the supply pipes 44 and 49, in accordance with the desired operation oi the circuit breaker.

As illustrated in the drawing, the circuit breaker is disposed in its closed position with the movable contact element 3 held in telescoping engagement with the stationary Contact element 2 by the piston y4, which is at the same time positioned at the upper end of the cylinder bore within the casting I. Suitable means, not shown, may be provided for releasably locking the movable contact element 3 in this position, If it is desired to operate the circuit breaker to contact open position, fluid under pressure is supplied through the supply pipe 44 by operation of the magnet valve device 41. The pressure iiuid thus supplied through the pipe 44 acts against the valve element 56 to shift downwardly the supply valve assembly so that fluid under pressure is supplied by way of the port 45, conduit 2I and passage 6 to the piston chamber 5 for shifting the piston 4 and contact element 3 downwardly. At the same time, the valve portion 5l is carried to its lowermost position for connecting the chamber I below the piston 4 t0 the atmosphere by way of passage 8, conduit 26 and port 5|. Fluid under pressure supplied to the conduit 2l also flows through the conduit 26 and past the check valve 22 to the pressure chamber lil within the casing section I3 and exerts an upward force on the movable abutment Il.

The piston Il is thereby moved downwardly to disengage the movable contact element 3 from the stationary contact element 2, and as it approaches the lower'end of its stroke, the piston engages the movable abutment Il and begins to move that element downwardly while closing the port 9. As hereinafter explained, the pressure area of the movable abutment I'l is greater than that of the piston 4 and thus exerts an upward force exceeding that of the iluid pressure moving the piston downwardly, but under normal conditions the piston A as it approaches the lower limit of its stroke will be subject to an additional force due to the inertia and kinetic energy of the moving parts, so that upon engagement of the piston Il with the movable abutment both elements will be carried downwardly against the opposing pressure of fluid within the chamber I 4 and of the light spring I i3. As the piston fl and movable abutment Il' are thus moved downwardly against the entrapped fluid within chamber id this fluid is further compressed and provides a cushioning force for rapidly and smoothly decelerating the moving elements, thereby arresting the opening movement of the circuit breaker without damaging impact or vibration. The maximum pressure of iluid in the chamber I4 is predetermined, in accordance with the amount of kinetic energy to be absorbed, by operation of the check valve 30, which may be set by means of the screwthreaded adjusting element 3l. By starting with a fluid pressure of several atmospheres under the abutment Il and controlling the nal pressure by means of the check valve 35, the maximum kinetic energy may be absorbed with a minimum overtravel. Any tendency of the piston l and associated elements to rebound may be made negligible by so loading valve 3B by adjusting element 3l that the compressed iluid in chamber I5 is almost exhausted by the time the kinetic energy of the moving parts is absorbed. It will be understood that as the pressure of fluid within chamber Il! is increased, as just explained, the two check valves 22 and 21 prevent venting of fluid therefrom by way of the pipes 20 and 25.

It may be assumed that when the downward stroke of the piston 4 is terminated, the piston and movable abutment I 1 will remain disposed somewhat below the position occupied by the movable abutment in the drawing, due to the weight of the associated elements. This final psition may be 'determined by the iluid pressure in chamber I4 and the value of the spring I3.

When it is desired to effect closing operation of the circuit breaker, with the supply pipe lid vented to the atmosphere by way of the now deenergized valve device 41, fluid under pressure is supplied through the supply pipe 49 to the bore 48 of the valve device 38 by operation of valve device i), Pressure of fluid acting upwardly against the valve element 5l then shifts the valve assembly upwardly to vent the piston chamber 5, and to close the exhaust port 5I while causing flow of fluid under pressure through the port 52, conduit 26 and passage 8 to the port 9, which at this time remains blocked byv piston 4. At the same time, iiuid under pressure iiows by way of conduit 26 and conduit 25 past the check valve 2l to the pressure chamber I4, and acts upwardly against the movable abutment I'l to move that member, together with the piston 4 and movable contact element 3, upwardly with a force determined by the relatively large pressure area of the movable abutment. As the piston Il is thus -carried past the inlet port 9, the pressure of fluid supplied to the chamber 'I by way of the passage becomes eiective to shift the piston away from the movable abutment I1, which meanwhile is brought to rest on the lower end of the cylinder wall enclosing the chamber "I, after whichupward movement of the piston 4 is continued at the rapid speed to which it has been accelerated by initial operation of the movable abutment.

From the foregoing it will be seen that a fluid pressure operated moto-r for a circuit breaker constructed in accordance with the invention may be associated with any type or circuit breaker mechanism involving a single pole unit, as shown in the drawing, or a multiple of such units independently operative from the single sourceA or fluid under pressure.V The circuit breaker operating mechanism comprises a cylinder and the usual piston for actuating a movable contact element, with which are associated an auxiliary movable abutment operatively aligned with the piston and a casing structure providing a pressure chamber to which fluid under'pressure is supplied simultaneously with the supply of fluid for operating the piston. By the provision of suitable valves for limiting the maximum pressure to which the movable abutment can be subjected, and forming the abutment with a pressure area exceeding that of the circuit breaker operating piston, the apparatus is rendered operative to establish a desired cushioning force for arresting the movement of the operating elements of the circuit breaker at the end of an opening operation, in a safe and shock-free manner. Upon initiation of a closing operation, the relatively large movable abutment is again subjected to the pressure of iluid supplied for operating the piston in the opposite direction, and serves to accelerate the piston and the contact element of the circuit breaker, thus overcoming static friction and the inertia of the operating parts to facilitate rapid operation. It will be understood that a combination shock absorber and accelerating device having a construction similar to that already described may be installed at the upper end of a circuit breaker operating motor as well as at the lower end,`if it is found desirable to provide the advantages of this mechanism for each cycle of the operation of the equipment.

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 and arrangement of parts thereof may be made without departing from some of the essential features of the invention.

I claim as my invention:

l. In a circuit breaker having a movable contact member, a cylinder constructed and arranged to be supplied with fluid under pressure and a piston mounted in said cylinder for actuating said contact member, fluid pressure means adapted to be engaged by said piston at least during the latter part of an operating stroke, means for conditioning said fluid pressure means with iiuid under pressure for yieldingly resisting nal movement of said piston as it approaches the end 'of said operating stroke, rand'. means whereby. said fluid pressure means appliesan. initial accelerating force: to said: piston `at: thebeginnng :ofzthe return stroke in the oppositedirection.

A2. In acircuit lbreaker having ia movablecontact member, a cylinder constructed `and arranged to be supplied'with fluid under pressureianda piston mounted insaid cylinderl for actuating said contact member, and uidlpressurefimeans..con-

:ditioned by. fluid under pressure suppliedto said cylinder` for yieldingly resistingL na1 movement of saidpiston Vas itapproaches the .end of -an operating. stroke, said 'fluid pressure means: applying initial accelerating 'force f-to saidL'pis-ton J at the beginning of i the return stroke in 'ther opposite direction.

.3. In a circuit breaker' having .a movable contact member, a cylinder constructed and arranged to be.v supplied with fluid underfpressureand a piston mounted in said cylinder for actuating said contact member, fluid pressure means conditioned by iluid under pressure supplied to'sai'dy cylinder for yieldingly resisting iinal-movement of said piston .as it approaches-the end of-'an 'operating stroke, saidmeans comprising 'ai movable abutment having-a pressureareaV larger than' that of said piston, means foratone time @subjecting said abutment tofafluid pressureopposing that for operating said piston, .and means for subjecting said movable abutment at anotherl time to-Aa fluid pressure for augmenting the fluid-pressure applied to said piston.

4. In a circuit breaker' having amovable'contact member, a cy1inder,a piston in said cylinder for actuating themovableI contact-member, fluid 1 pressure means for yieldingly resisting nal movement of said piston las it approaolies'the-end'of an operatingstroke, a control valve-'and conduit means extending therefrom for supplying-fluid under pressure both`v toV said cylinderi for4 moving 5. "A fluid pressuremotor comprising amain cylinder, a larger cylinder'disposed coaXially of said main'cylinder, an `operating .piston sli'dably mounted in said main cylinder and movable' into said larger cylinder at one end ofits stroke,-a

movable abutment mounted in said larger cylinder and engageable by said piston, means for supplying fluid under pressuretolsaid maincylinder for moving said piston towardsaid movable abutment and to said' larger cylinder -for subjecting said movable abutment to. uidlpressureopposing movement of said pistonafterengagement thereof with said abutment, means foi-.limitingthe pressure Vof uid in. said larger. cylinder toA .a predetermined value, andl-meansfori'lrst supplying liuid under pressureto saidlargercylinder for rendering said movable abutment operative to accelerate said piston-to initiate operation thereof in a return stroke and for subsequently supplying fluid under pressure to-said main cylinder for ccntinuing movement of saidpiston independently oi said abutment.

6. A fluid pressure-motor comprising a'main cylinder, alarger cylinder disposedzcoaxially-'of said main cylinderfan operating'piston slidably V8 mounted. inV said main cylinder and movable into Isaid larger cylinder at one' end lof its stroke, a

'movableabutment mounted in said larger cylinder and engageable'tby-said piston, valve meanslfor controlling the supply of fluid under pressure to said main cylinder and to said larger cylinder at opposite sides of said piston and of said movable abutment to move said piston in a given direction andlarrest its motion at the end of said stroke, and

other valve means operative to further control the supply -of fluidfun'der pressure to said larger cylinder tocause said movable abutment to exert aforce onsaid piston to initiate movement ofthe piston in the opposite direction to effect a return stroke.

'7.In afcircuit'breaker, in combination, mov- 'able contact means, a main cylinder, avpiston Vmounted in said cylinder and operatively connected tosaid contact means, a larger cylinderl -disposed coaxially of said main cylinder, a movable abutment -mounted in said larger cylinder 'and'- having Aa pressure area greater than that of said piston, said piston being engageable' with said vmovable abutment and movable partly into said vlarger -eylinder,means for supplying fiuid under pressure to saidv main-cylinder at lone side Vof said piston'for operating same toward said movable abutmenameans for supplying fluid under pressure" to said larger cylinder for causing said movable abutment to yieldingly arrest the nal movement of said piston upon engagement thereof with saidabutmenumeans for venting said cylinder at said one side `ofy said piston while supplying fluid under pressure to said larger cylinder'for causing said movable abutment to accelerate said piston ininitiating a return stroke, and means for thereafter supplying fluid under pressure to said cylinder at the other side of said piston for continuing movement thereof in the return stroke.

V8. Ina circuit breaker, in combination, movable Contact means, a main cylindena piston mounted in said cylinder and operatively connected to said contact l means, a larger cylinder disposed coaxially of said main cylinder, a movable-abutment mounted in `said largercylinder yand'havinga pressure area-greater than thatcf said piston, said .piston being engageable with said movable abutment andmovable vpartly into said larger cylinder, means for supplying fluid underv pressure tolsaid main cylinder at one side of said piston for .operating same toward said movableabutment, means v'for supplying fluid under pressure to said-larger cylinder for causing said movable abutment to yieldingly'arrest the final movement of said piston upon engagement thereof with said abutment, means for venting said cylinder at said 'one side of said piston while supplying uid under pressure'tosaid larger cylinderfor causing said movable Vabutment to accelerate. Saidpiston during a return stroke, means for thereafter supplying fluidunderqpressure tosaid cylinder at the other side of said piston' for continuing'movement thereof in the .return stroke, Aand adjustable means'for limiting the vpressure of iiuid in said -larger cylinder.

`l9. In a 'circuitbreaker having a moving contact member, a cylin'deradapted to be supplied with fluid under pressure, a piston operative within saidlcylindervfor actuating said contact member, fluid pressure meansv conditioned by fluid under .pressurevsu-pplied to saidI cylinder for yieldingly resistingnal mOVernent-Gf-saidpiston as it-ap- .preaches the end of an operating stroke, said fluid pressure `means including a movable abutment 9 operatively engageable with said piston for movement thereby, and means whereby said movable abutment applies an initial accelerating force to said piston at the beginning of the return stroke in the opposite direction.

10. A circuit interrupter comprising separable contact means, a main cylinder, a piston in said cylinder and operably connected to said contact means for moving said Contact means to open and closed circuit positions, a second cylinder adjacent one end of said main cylinder, a movable abutment in said second cylinder, means normally biasing said abutment to a position closing said one end of said main cylinder, means for supplying fluid under pressure to said main cylinder at one side of said piston for operating said piston toward said movable abutment to actuate said contact means to open position, means for supplying uid under pressure to said second cylinder to cause said movable abutment yieldingly to arrest the nal movement of said piston upon BENJAMIN P. BAKER.

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

UNITED STATES PATENTS Number Name Date 899,795 Osmer Sept. 29, 1908 913,853 Rowntree Mar. 2, 1909 20 2,113,161 Osborne Apr. 5, 1938 2,292,096 Thumin et a1 Aug. 4, 1942

Images