US2681958A

US2681958A - Circuit breaker with blast valve actuated by a fluid motor and a spring

Info

Publication number: US2681958A
Application number: US276893A
Authority: US
Inventors: Leonard J Linde
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1952-03-15
Filing date: 1952-03-15
Publication date: 1954-06-22
Anticipated expiration: 1971-06-22
Also published as: FR1075551A; GB734372A; DE1027282B

Description

June 22, 1954 LINDE 2,681,958

L. J. CIRCUIT BREAKER WITH BLAT VALVEACTUATED BY A FLUID MOTOR AND A SPRING Filed March 15, 1952 2 Sheets-Sheet l llhhlm J 1954 J LlNDE 2,681,958

L. CIRCUIT BREAKER WITH BLAST VALVE ACTUATED BY A FLUID MOTOR AND A SPRING Filed March 15, 1952 2 Sheets-Sheet 2 Patented June 22, 1954 CIRCUIT BREAKER WITH BLAST VALVE ACTUATED BY A FLUID MOTOR AND A SPRING Leonard J. Linde, Needham, Mass., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application March 15, 1952, Serial N 0. 276,893

Claims.

This invention relates to circuit interrupting devices and more particularly to blast valve operating mechanism for electric circuit breakers of the fluid operated type.

In a fluid operated electric circuit breaker a source of fluid under pressure is usually connected to a fluid motor foractuating the arcing contacts to open circuit position and to open a blast valve to provide a blast of fluid under pressure'adjacent the arcing contacts to extinguish the arc. Heretofore, a shaft driven by the fluid motor provide the torque to separate the arcing contacts and the power to crack open the blast valve. The blast-valve cracking operation puts a high, short time load on the operating shaft and fluid motor and necessitates providing a structure strong enough to withstand the stress and strain of the momentary'high load. Usually the operating shaft and motor, when designed to separate the arcing contacts and crack open the blast valve, become too bulky to fit into the streamlined structures of the modern circuit breaker structures;

In order to reduce the circuit breaker structure size and to retain or increase its interrupting ability a new and improved operating mechahim; is provided which utilizes a short stroke fluid motor for initially cracking 'a blast valve and another fluid operated motor and shaft assembly for separating the contacts and actuating the blast valve the remainder of its travel to its fully open position.

It is, therefore,-one object of the present invention to provide a new and improved operating mechanism in which one device initially actuates an element and another device completes the element actuation.

Another object of the present invention is to provide a new and improved pneumatic operating system for circuit breakers of the fluid blast type in which a first means cracks a blast valve and a second means actuates the blast valve to its fully open position.

Another object of the present invention is to provide a new and improved operating system for a fluid blast type of circuit breaker in which the contact actuating shaft is relieved of the blast valve cracking operation.

A further object of the present invention is to provide a new circuit breaker operating system in which a pneumatic means cracks a blast valve open and controls the actuation of a second pneumatic means which, in turn, separates the arcing contacts and moves the blast valve to its fully open position.

A still further object of the present invention is to provide a new and improved streamlined circuit breaker structure which is compact, efficient andreliable.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. l is a diagrammatic view partly in elevation of a circuit interrupting system embodying the present invention;

Fig. 2 is an enlarged detailed view of the blast valve assembly illustrated in Fig. 1; and

Fig. 3 is a right end view of the blast valve assembly illustrated in Fig. 2.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a circuit breaker including as a constructive element thereof a reservoir 6 constituting a source of supply of fiuid under pressure, which will be assumed herein to be compressed air supplied from a suitable compressor (not shown). Although in general, circuit breakers of the type herein considered are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure or pole unit is shown in the figure and the circuit breaker will be described in detail as if it were of the single pole unit type. A The circuit breaker comprises a fixed arcing contact '1 and a cooperating movable arcing contact 3 connected in an electric circuit through terminal studs 9 and Ill. The arcing contacts are mounted to engage within an arcing chamber H which is'aligned with an arc chute l2. The arcing chamber 1 I is axially aligned with a hollow insulator 13 which provides a connection between reservoir 6 and arcing chamber H through a suitable blast valve [4 for directing a blast of arc extinguishing fluid under pressure between the arcing contacts and through the arcing chamber II.

The blast valve l4 requiring a relatively high force to effect initial movement thereof and a relatively small force to efiect completion of the movement thereof, is initially actuated by a high power, short stroke fluid motor l5. Blast valve 14 controls a blast inlet port It. Mortor l5 coaxially arranged with blast valve M comprises a cylinder I 9, a blast valve cracking piston 20, a piston rod ill, a spring 22, and an inlet port 2d. Piston 20 is slidably mounted onpiston rod 2!, but may engage a shoulder provided on the piston rod.

A solenoid operated valve 25 opens automatically if a fault current occurs on the power circuit controlled. Valve 25 controls the flow of fluid under pressure from reservoir 6 through a pipe line 21, valve 25, pipe line 28, a three way valve 29, and inlet port 24 of cylinder it to act on the blast valve cracking piston 2i! of fluid motor [5.

Valve 29 is connected by linkage 30 to a lever 5! mounted on a rocking shaft 3L, A linkage 32 connects rocking shaft 3| with the movable sickle shaped arcing contact 8. If arcing contact 8 is in the closed position thereof, valve 29 is in such an angular position as to admit compressed air to cylinder I 9 through inlet port 24. Upon opening of valve compressed air from the reservoir 6 is also admitted to a pipe line which is connected to a slide valve 31.

Piston 20 of fluid motor I5 is provided with. a push pin 38 arranged to actuate a lever 39 pivotally mounted at 40. The blast valve cracking motion of piston 20 causes pin 38 to pivot lever 39 about point 40 in counterclockwise direction resulting in movement of a piston rod 4| and piston 42 of slide valve 31 from left to right.

Fluid under pressure in pipe line 35 may then pass through slide valve 31 into a pipe line 43, pipe line 44, inlet port 36 to a fluid motor 45.

Fluid motor 45 comprises a cylinder 41, a piston 48 having a piston rod 49 movable therewith and connected through a connecting rod 50 and a crank 5| to shaft 3|. Motor 45 is provided with a dumping valve 52 which releases pressure above piston 48 at or near the end of its upward stroke. Dumping valve 52 is biased against its valve seat 53 by a spring 54. Dumping valve 52 is provided with ports 55 which are controlled by a plate 56 biased in port closing direction by a spring 51. The lower part of cylinder 41 is vented by a valve 46.

Shaft 3| is provided with a cam or trigger 60 which upon rotation of shaft 3| in contact opening direction releases a lever or detent 6| which in turn releases a compressed spring 62. Spring 62 serves as a second low power motor having a long stroke and acts on piston rod 2| to move the blast valve to its fully open position after a blast valve cracking operation and to maintain blast valve M in its open position, even upon dumping of air from the high pressure side of piston 20. Spring 62 may begin to actuate blast valve I4 to its fully open position after blast valve I4 has been cracked but before motor I5 has completed its operating stroke. Motor I5 initially actuates blast valve I4 to separate valve element I04 from its valve seat a relatively short distance or gap length and spring 62 and its lever system further actuates valve I4 to separate valve element I04 from its valve seat a relatively long distance or gap length.

Closing of the arcing contacts is initiated by energizing a solenoid operated valve 63 which is substantially identical to valve 25. Valve 63 connects reservoir 6 to one end of a fluid motor 64.

Fluid motor 64, through the intermediary of linkage 59, causes rotation of shaft 3| to close the arcing contacts 1, 8. Motor 64 comprises a cylinder 65, a piston 66, a dump valve 81, valve seat 68, spring 69, valve ports 10 and inlet port 1|. The other end of closing motor 64 is connected through an outlet port 12 to a valve 15 comprising a valve element 16, a valve stem 11, and a spring 18 which biases valve element 11 in valve closing direction. In the closed position of the breaker, the piston 66 of fluid motor 64 is in its lower position acting upon valve stem 11 to keep valve 15 open.

Consequently, air can flow through pipe line 43 into the cylinder 65 of fluid motor 64. As the piston of fluid motor 64 moves toward contact open position, valve element 16 is caused to close by spring 18 and will be completely closed at the instant that piston 66 disengages from the valve stem 11. The fluid admitted through valve 16 is slowly vented through a valve 13.

The solenoid operated valves 25 and 63 are substantially identical so that only one valve will be described. Valve 25 comprises a casting forming a cylinder provided with fluid admission openings or ports BI and. 82 and with an exhaust opening or port 83. Port 8| is connected to pipe line 21 and port 82 is connected to pipe line 28. Cylinder 80 is provided with a differential piston or valve member 84 which has a small aperture and is biased by a spring 85 to close port 82. Cylinder 80 is further provided with a pilot valve 86, the opening of which initiates operation of the valve member 84. A spring 81 biases valve 86 to valve closed position and valve 86 is actuated to valve open position by the energization of a coil 88 which, in turn, is responsive to abnormal conditions in the power circuit controlled by the circuit breaker structure.

Figs. 2 and 3 illustrate in detail the structural elements of the blast valve assembly. The blast valve is fully opened by any suitable energy storing means such as a spring 62 arranged in a housing 0 Lever BI is made up of two parallel plates pivoted at 92 and one end of spring 82 rests on and acts upon an intermediate point of lever 6|. The other end of spring 62 is anchored at 83. The lower end of lever 6| is attached to a pair of links 94 by means of pins 95 driven in holes of the links. Links 94 are provided with other holes into which a pin 31 is inserted through a collar 98 slidably mounted on piston rod 2| and through an oblong hole 36 in piston rod 2|. This con.- stitutes a lost motion connection between lever BI and piston rod 2 A second collar 98 is pinned at I00 to piston rod 2| and a helical spring |0| is arranged between

collars

98 and 99, thus providing a flexible element in the chain of elements which constitutes the operating mechanism of the blast valve l4.

Lever 6| is provided with a roller I02 which coacts with cam 60. The blast valve |4 remains closed as long as roller I02 and lever 6| are held in position by means of cam 60. If roller I02 is released by rotation of cam 60 so that the roller I02 travels within a groove I03 in cam 60, lever 6| is free to move in clockwise direction about its fulcrum point 92 under the action of spring 62 biasing blast valve I4 to its valve open position. Spring 62 is not sufficiently strong to crack blast valve I4 open, but it can maintain the blast valve I4 open once it has been cracked open by the action of piston 20 of fluid motor I5.

Upon the occurrence of a fault condition on the power circuit, solenoid coil 88 of the valve 25 is energized thereby moving pilot valve 86 to the left to exhaust the air from behind valve element 84. The pressure acting on the left side of valve element 84 overcomes the action of

springs

85 and 81 and the valve element 84 is moved to the right to open port 82. Air under pressure from reservoir 6 passes through port 82, pipe line 28, three way valve 29, inlet port 24- to fluid motor l5. Piston 20 under the force of the fluid under pressure from inlet port 24 gives a hammer blow to the shoulder of shaft 2 The shaft moves toward the left to crack the blast valve |4 open while lever 6| remains stationary.-

Piston 23 also causes pin 38 to pivot lever 30 about 40, resulting in movement of slide valve 31 from left to right. Compressed air is admitted through pipe line 35, slide valve 31, pipe line 43, and pipe line 44 to fluid motor 45. Air under pressure passes through ports 55 and actuates plate 56 downward against the bias of spring 51. Fluid under pressure above piston 48 actuates piston 48 downward, causing piston rod 49 to rotate shaft 3| clockwise to separate the arcing contacts 1, 8.

:Air is also admittedmomentarily through pipe 43 and valve .15 into the lower part of cylinder 65 to cause motor 64 toexert'animpulse aiding the action of motor 45. As a result of the movement of shaft 3| and cam 60 mounted thereon, lever 6| drops into groove 1.03 of cam 60, thereby releasing spring '62 so that it rotates lever 6| clockwise. Clockwise rotation-of lever 6| actuates links 94 to the left. This action disconnects shaft 2| and blast valve element 104 from piston before the piston has completed its short stroke action. Blast valve element [04 moves to its fully open-position while piston 20 completes its stroke and thereafter remains stationary. Spring .62 maintains blast valve- [4 open even upon dumpingof the air from the right side of piston 20.

As shown in the'drawings, cam 60 has a radially outer surface and a radially inner surface. As long as roller I02 rides on theradially outer. surface, lever Si is in alocked position and spring 62 cannot act uponpiston rod 2! of blast valve l4. If the radially outer surface of cam 60 disengages from cam roller 32, as happens during a contact separating action, the roller I02 drops down into the groove N13 to the radially inner surface, permitting spring 62 to expand and open and to keep open the blast valve.

Near the end of the opening stroke of the breaker the three way valve 29 is rotated approximately ninety degrees clockwise and in so doing dumps the air to atmosphere from the right side of piston 20 of fluid motor I5. Toward the end of the openingstroke the cam roller N12 is raised from theradially-inner surface of groove I03 of cam '60 to the radially outer level of cam 60, resulting in reclosing of the blast valve M.

The circuit breaker arcing contacts are closed by energizing the coil I05 of solenoid valve 63. This valve operates in the same'manner as valve to'allow fluid under pressure from'reservoir 6 to pass into the fluid motor 64. The actuation of fluid motor 64 closesthe arcing contact I, 8.

During the closing stroke of the breaker the radially outer surface of the cam '60 and the cam roller [02 disengage'but roller )2 does not drop down to the lower camlevel and blast valve 14 does not open because spring 52 is not 'ISllfllciently strong to open blastvalve 14 against the tank pressure acting on its valve element I04.

In accordance with the invention claimed, a new andimproved circuit interrupting device is provided in which a blast valve corltrolsthe flow of fluid from a source toapoint adjacent'arpair of arcing contacts. A first fluid operated .motor comprising a cylinder and a piston is provided forcracking the blast valve open, and'a second fluid operated motor arranged to operate :in sequence'with the blast valve comprising a :cylinder and a piston is provided for separating the arcing contacts. A valve means for controlling the time at which fluid under pressure is supplied to the second motor is connected to the piston of the first motor so that the valve is acuatedxupon a predetermined movement of the piston of the first motor. Spring means controlled by the actuation of the secondmotor in'contact opening direction are provided for actuating the blast valve to its fully open position, thus providing onemotor for cracking the blast valve open and a second motor for separating the arcing contacts and .moving the iblast valve to its fully opened position.

Although but one embodiment of the present invention hasbeen illustrated. and described, it

will be apparent to those skilled in .the :artthat various changes and .modifications may .be ..made thereinwithout departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In afluid blast circuit interrupter, the combination comprising: 'a source of fluid under pressure, separable arcing contacts for establishing an are, a blast'valve for controlling a'fluid blast from'said source for extinguishing the are drawn upon separation of said arcing contacts, a first fluid operated motor comprising a cylinder and a piston for cracking said blast valve, asec- 0nd fluid operated motor arranged to operate in sequence with said blast valve comprising a cylinder and a piston for separating'said arcing contacts, valve means for controlling the time at which fluid under pressure is supplied to said second motor, means interconnecting said valve means and said piston of said first motor for actuating said valve means upon actuation of said first motor, means for moving said blast valve to fully open position aftera blast valve cracking operation, and means for actuating said blast valve moving means after said piston of said second motor has moved a predetermined 'distance in contact opening direction.

v2. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said arcing contacts, a first fluid operated motor comprising a cylinder and a piston for cracking said blast valve, a second fluid operated motor arranged to operate in sequence with said blast valve comprising a cylinder and a piston for separating said arcing contacts, valve means for controlling the time at which fluid under pressure is supplied to said secondmotor, meansinterconnecting said valve meansand said piston of said first motor for actuatingsaid valve means upon actuation of said first motor, spring means 'for moving saidblast valve to fully open position after a blast valve cracking operation, and trigger means connected to said second motor for actuating said spring means after a predetermined movement of said piston of said second motor.

3. In a fluid' blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable .arcing contacts for establishing an arc, aiblast valve for controlling a fluid blast fromsaid source for extinguishing the are drawn upon separation of said arcing contacts, a first fluid operated motor comprising .a cylinder and a piston for cracking said blast valve, a second fluid operated motor arranged to operate in sequence with said blast valve comprising a cylinder and a piston for separating said arcing contacts, valve means for controlling the time at which fluid under pressure is supplied to said second motor, means interconnecting said valve means and said piston of said first motorffor actuatingsaid valvemeans upon actuation of said flrstmotor, spring means for moving said blast valve to its fully open position, and trigger means actuated upon cracking-of said blast valve for releasing saidspring means to move said .blast valve to fully open position.

4. In afluidblast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the arc drawn upon separation of said arcing contacts, a first fluid operated motor means com prising a cylinder and a piston for cracking said blast valve, a second fluid operated motor means arranged to operate in sequence with said blast valve for separating said arcing contacts comprising a cylinder and a piston, a shaft mounted for rotating upon movement of said second motor means, a cam secured to said shaft, valve means for controlling the time at which fluid under pressure is supplied to said second motor, means interconnecting said valve means and said piston of said first motor for actuating said valve means upon actuation of said first motor, spring means for moving said blast valve to its fully open position, and a detent coacting with said cam upon. movement of said shaft for releasing said spring means to move said blast valve to fully open position.

5. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said arcing contacts, a first fluid operated motor means comprising a cylinder and a piston for cracking said blast valve, a second fluid operated motor means arranged to operate in sequence with said blast valve for separating said arcing contacts comprising a cyl inder and a piston, a shaft mounted for rotation upon movement of said second motor means, a cam secured to said shaft, means arranged upon release thereof to move said blast valve to its fully open position after a blast valve cracking operation, and a detent coacting with said cam upon movement of said shaft in contact opening direction for releasing said means to move said blast valve to fully open position.

6. In a fluid blast circuit interrupter the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an are, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said arcing contacts, a first fluid operated motor means comprising a cylinder and a piston for cracking said blast valve, a second fluid operated motor means arranged to operate in sequence with said blast valve for separating said arcing contacts comprising a cylinder and a piston, a shaft mounted for rotation upon movement of said second motor means, a cam secured to said shaft, energy storing means for actuating said blast valve to fully open position after a blast valve cracking operation, and a detent coacting with said cam upon movement of said shaft in contact opening direction for releasing said energy storing means to actuate said blast valve to its fully open position.

7. A valve operating mechanism comprising a valve having a movable valve element adapted to cooperate with a valve seat to seal a source of fluid under pressure, a first fluid motor comprising a cylinder and a piston arranged in coaxial relation with said valve element and having a relatively short stroke for causing initial separation of said movable valve element from said valve seat, means for detachably connecting said piston of said first motor to said valve element, a second motor having a relatively long stroke for causing a substantially increased separation of said movable valve element from said valve seat, and means responsive to the movement of Cir said piston for detaching said valve element from said first motorbefore said first motor has completed its short stroke action.

8. A valve operating mechanism comprising a valve having a movable valve element adapted to cooperate with a valve seat to seal a source of fluid under pressure, a first fluid motor comprising a cylinder and a piston arranged in coaxial relation with said valve element and having a relatively short stroke for causing initial separation of said movable valve element from said valve seat, means for detachably connecting said piston of said first motor to said valve element, a second motor having a relatively long stroke for causing a substantially increased separation of said movable valve element from said valve seat, and means actuated by said second motor for detaching said valve element from said first motor before said first motor has completed its short stroke action.

9. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an arc, a blast valve for controlling a fluid blast from said source for extinguishing the are drawn upon separation of said arcing contacts, a first fluid operated motor comprising a cylinder and a piston having relatively short stroke action for cracking said blast valve, a second fluid operated motor arranged to operate in sequence with said blast valve comprising a cylinder and a piston for separating said arcing contacts, valve means for controlling the time at which fluid under pressure is supplied to said second motor, means for detachedly connecting said piston of said first motor to said valve means, means for moving said blast valve to fully open position after a blast valve cracking operation, means for actuating said blast valve moving means after said piston of said second motor has moved a predetermined distance in contact opening direction, and means for detaching said valve means from said first motor before said first motor has completed its short stroke action.

10. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establishing an are, a blast valve for controlling a fluid blast from said source for extinguishing the arc drawn upon separation of said arcing contacts, a first fluid operated motor comprising a cylinder and a piston having a relatively short stroke action for cracking said blast valve, a second fluid operated motor arranged to operate in sequence with said blast valve comprising a cylinder and a piston for separating said arcing contacts, valve means for controlling the time at which fluid under pressure is supplied to said second motor, means for detachedly connecting said piston of said first motor to said valve means, means for moving said blast valve to fully open position after a blast valve cracking operation, means for actuating said blast valve moving means after said piston of said second motor has moved a predetermined distance in contact opening direction, and means actuated by said blast valve moving means for detaching said valve element from said first motor before said first motor has completed its short stroke action.

Number Name Date Logan Oct. 30, 1906 Vincent June 20, 1916