US2586361A - Fluid pressure operated circuit breaker - Google Patents

Description

Feb. 19, 1952 D. J. MARSDEN FLUID PRESSURE OPERATED CIRCUIT BREAKER Filed Feb. 28, 1948 2 SHEETS-SHEET l WML ATTORNEY Feb. 19, 1952 D, J, MARSDEN 2,586,361

FLUID PRESSURE OPERATED CIRCUIT BREAKER ATTORNEY' Patented Feb. 19, 1952 FLUID PRESSURE OPERATED CIRCUIT BREAK Douglas J. Marsden, San Francisco, Calif., as-

signor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 28, 1948, Serial No. 12,085

9 Claims.

This invention relates to circuit breakers and more particularly to circuit-breaker operating means of the fiuid or gas pressure type.

In designing compressed gas operated circuit breakers, a combination of operating gas pressure and operating piston area must be selected which will provide suirlcient driving power to overcome the heavy contact load which is picked up during the latter part of the closing operation after the contacts touch. If the breaker is to be used for quick reclosing service, sufficient power must be developed to quickly reverse the movement of the breaker on quick reclosing voperations which are preferably initiated at an intermediate point in the opening stroke. If the large driving force required for these conditions is applied during the first part of the closing stroke on normal closing operations from the full open positionI the circuit breaker will be operated at such a high speed and the kinetic energy developed will be so great that it may result in destructive slamming of the breaker and mechanism.

` Another difculty in compressed gas operating systems is to maintain the compressed gas in the supply reservoir substantially at a predetermined pressure. Stored gas pressure is reduced by each breaker closing operation. When several closing operationsor reclosing operations take place within a short period of time, the stored gas pressure will be reduced due to the inability of the compressor unit to maintain the pressure in the reservoir at the normal level. As a result, this mechanism may be called upon to operate when the pressure in the storage tank is as low as 80 percent of normal pressure. On the other hand, the pressure in the storage tank may increase to 110 percent of normal due to high ambient temperature. Thus the operating mechanism may be required to operate at gas pressures ranging 4from approximately 8O to 110 percent of normal pressure. If the pressure is high, this may result in excessive closing speed and slamming of the breaker parts, and, if the pressure is low, slow contact speed will result in excessive arcing and possible damage to the circuit breaker.

An object of the invention is to provide a circuit breaker with a fluid pressure operating mechanism embodying means which will automatically vary the rate of flow of compressed fluid to the operating mechanism in accordance with variations of fluid pressure in the fluid pressure supply system.

Another object of the invention is to provide a circuit breaker with a fluid pressure operating means embodying means for automatically maintaining the driving power delivered to the operating mechanism substantially the same when the fluid pressure in the supply system decreases or increases a substantial amount below or above normal pressure or when the pressure is at normal value.

Another object of the invention is to provide a circuit breaker having a uid pressure operating means and means for admitting compressed gas to the mechanism at a predetermined rate during the first part of the closing operation and at an increased rate at the latter part of the closing operation and during a quick reclosing operation, and means operated in response to the gas pressure in the compressed gas supply system for varying the supply of compressed gas admitted to the mechanism inversely to the gas pressure in the compressed gas supply system.

Another object of the invention is to provide a circuit breaker with a compressed gas operating mechanism having an inlet passage for admitting y compressed gas to the mechanism and means operated in response to pressure in the gas reservoir for automatically varying the size of the inlet passage inversely as the pressure in the gas reservoir varies above or below normal p-ressure.

Another object of the invention is to provide a compressed operating mechanism for a circuit breaker having an inlet passage for admitting compressed gas to said operating mechanism with a valve disposed in said inlet passage operable by the circuit breaker to vary the amount of compressed gas admitted to the mechanism according to the position of the breaker, and a second valve disposed in the inlet passage operable by fluid pressure from the fluid pressure supply system to vary the amount of compressed gas admitted to the mechanism according to the pressure in the fluid pressure supply system.

Another object of the invention is to provide a circuit breaker with an improved compressed gas operating means embodying automatic means for delivering the proper amount of power to the mechanism to maintain proper speed of operation despite variations in operating load and variations in the available gas pressure.

Further objects and advantages of the invention will become apparent from the following detailed description of one embodiment thereof when read in conjunction with the accompanying drawings.

In said drawings:

Figure 1 is an elevational view, partly insection, of a compressed gas circuit breaker operating mechanism embodying the invention, the circuit breaker being shown schematically.

Fig. 2 is a fragmentary detail sectional view taken on line lI-II of Fig. l.

Fig. 3 is a schematic view of the compressed gas supply system.

Fig. 4 is a fragmentary sectional view illustrating a modilication or" the invention.

The present invention is illustrated as applied to a circuit breaker operating means similar to that disclosed in Patent No. 2,408,199, issued September 24, 1946 to James M. Cumming and Richard C. Cunningham and assigned to the assignee of the instant invention. In certain aspects. the present invention constitutes a iurther development and improvement over the compressed gas breaker operating mechanism ldisclosed in Patent No. 2,381,307, issued August 7, 1945 to Henry L. Peek and James M. Cumming and assigned to the assignee of this invention, and the invention is illustrated as applied to the same type oi compressed gas operating mechanism.

Referring to the drawings, tne circuit breaker represented schematically at 1 may be of any conventional construction either oi' the oil break or air break type. The circuit breaker, as schematically shown, comprises stationary contact means 9 and movable contact means Most conventional circuit breakers usually embody a contact pressure spring construction for mainl taining the desired pressure engagement of the contacts in the closed position. The main bridging contact is usually backed by springs to secure contact pressure. The contact pressure securing means is represented schematically in the drawing by the resilient laminated leaf spring construction of the movable contact means Although illustrated as a single pole circuit breaker,l it will,` of course, be understood that the breaker may be a multipole circuit breaker having a set of contacts 9 and for each pole thereol with the movable contacts mechanically connected for simultaneous operation in the usual manner. The circuit breaker is biased to open circuit position by means of an accelerating spring shown schematically at l5, and the breaker is mechanically connected to the operating mechanism indicated generally at I1 by a suitable connecting means. The connecting means is represented schematically as comprising a lever I9 pivoted at 2| on a nxed support, one end of the lever being pivotally connected to the breaker lift rod 23 and the other end being pivotally connected to an operating rod 25 which is, in turn, mechanically connected to the operating mechanism |1.

The operating mechanism comprises a main casting 21 which is formed to provide a cylinder 29 closed at the upper end by an integral part of the casting. A closing member 3| is secured to the lower end of the cylinder 29, this closure member having a relatively large port 33 therein open to the atmosphere. An operating or latching lever 35 is pivotally mounted at one end on the casting '21. The operating' lever consists of two spaced parallel levers 31 which are pivotally connected at one end by means of a pivot pin 39 to the upper end of a pair of links 4| (only one being shown) pivotally mounted on the main casting 21. The free ends of the levers 31 comprising the operating lever are connected by a cross member and carry a short shait 45 therebetween on which is rotatably mounted a latching roller 41 disposed between thej The breaker operating rod 25 is pivlevers 31.

otally connected by a pivot pin 49 to the midpoint of the operating lever 35, the pivot pin extending transversely through the levers 31 and engaging an opening in the lower end of the rod 25. The breaker operating lever is adapted to be held in closed position to hold the breaker closed by means of the high speed latching mechanism comprising a main latch 5| which is pivoted on the main casting 21 by a pivot pin 53. The latch 5| is adapted to extend between the parallel levers 31 and its latch end is adapted to engage and restrain the latching roller 111 carried by the free end of the operating lever 35. The latch 5| is biased to latching position by means of a spring pressed plunger 51. A stop 55 limits clockwise movement of the latch 5|. An auxiliary latch 61 is provided for normally engaging and holding the main latch 5| in latching position. The auxiliary latch 61 is pivoted on the casting 21 by a pivot pin 69 and has a latch projection 1| adapted to engage under a projection 13 of the latch 5|. A spring 15 biases the auxiliary latch 61 to latching position. The auxiliary latch is provided with a projection 11 which extends directly over the upper end of the trip plunger 19 of an electromagnetic trip device 8l.

The trip device 8| comprises, in addition to the trip plunger 19, an E-sliaped core 33 of magnetic material, an energizing winding mounted on the center leg of the core and the movable armature 81 cooperating with the core 83. The trip plunger 19 is secured to the center portion oi' the armature 81, and slidably extends upwardly through a guide opening in the center leg of the core 83 and through an opening in the horizontal portion of the main casting 21. A spring 89 biases the armature 81 downwardly to unattracted position.

When the trip device 6| is energized, the armature '81 thereof is moved upwardly against the core S3 causing upward movement of the trip plunger 19. This upward movement of the trip plunger moves the auxiliary latch 51 counterclockwise and disengages the projection 13 oi the main latch 5| whereupon the accelerating spring l5 of the circuit breaker moves the breaker to open position, the operating lever '35 being rotated counterclockw'ise about its pivoted end by the opening movement of the breaker. During the initial opening movement of the operating lever 35, the roller 41 pushes the main latch 5| in a counterclockwise direction as it clears the latch. In order to prevent the auxiliary latch 61 from returning to latching position until the breaker lever 35 is returned to closed position, there is provided a U-shaped balance lever 95, the legs of which are pivotally mounted on the extending ends of the pivot pin 69 on opposite sides of the auxiliary latch 61. The balance lever is biased counterolockwise by a compression spring 91 which is seated in a recess in the casting 21 and engages the under side oi a projection 99 of the balance lever. A cross member ||l| on the free end of the balance lever 95 is disposed directly beneath the free end or the operating lever 35 so that the balance lever will be held down in an inoperative position when the operat-- ing lever 35 is in closed and latched position. However, when the operating lever 35 is released, the balance lever 95 is rocked ccunterclcckwise and the portion 99 thereof engages and holdsl the auxiliary latch 61 in unlatching position until For this purpose, the biasing spring 91 is stronger than the auxiliary latch spring 15.

An operating piston |03 is reciprocably movable Within the operating cylinder 29, and this piston has a piston rod |01 which slidably extends in iluid-tight manner through an opening provided therefor in the top wall of the cylinder 29. The upper end of the piston rod |01 has a connecting element |09 threadedly connected thereto which is pivotally connected to the pivot pin 49 carried by the operating or latching lever 35. Thus the operating piston |03 is mechanically connected directly to the circuit breaker operating rod 25.

The operating piston |03 is adapted to be moved downwardly in the cylinder 29, to close or automatically reclose the circuit breaker, by compressed air from an air storage reservoir or tank III, the compressed air being admitted to the upper end of the cylinder 29 through an inlet passage I2 controlled by a main inlet valve indicated generally at I I3. The opening operation of the main inlet valve is controlled by a pilot valve I5 operated by an electromagnet or solenoid I I1.

Compressed air is stored and maintained in the air reservoir I I supplied by a conventional motor driven compressor shown schematically at ||4 (Fig. 3). y

The inlet and exhaust valve mechanisms are of the same general construction as that disclosed in Patent No. 2,408,199, issued September 24, 1946, to J. M. Cumming and R. C. Cunningham, and assigned to the assignee of the present invention. The inlet valve I I3 comprises a valve housing I9 and a main valve element I2| mounted in the valve housing. The main valve element I2| is adapted to be operated to open position by an air actuated valve piston (not shown) upon energization of the valve controlling electromagnet ||1, and the valve is returned to closed position by spring means (not shown) upon deenergiza tion of the electromagnet ||1.

In order to provide for quick reversal of movement of the operating .piston |03 and circuit breaker 1 to provide the effect of trip-free operation of the circuit breaker, the mechanism is provided with an air pressure exhaust means which causes quick collapse of air pressure in the operating cylinder above the piston |03 whenever the trip device 8| is operated so as to dump the pressure air to atmosphere and thereby permit quick opening of the circuit breaker. The air pressure exhaust means comprises air pressure exhaust ports |23 formed in the side of the operating cylinder 29 which are adapted to be connected to atmosphere by a main exhaust valve (not shown). The main exhaust valve is automatically opened by the air pressure above the operating piston |93 when a pilot valve |25 is opened in response to operation of the trip device 8|. The exhaust ports |23 are of larger size than the compressed air inlet passage |I2 so that the breaker will be opened quickly upon operation of the trip device 8| even though the main inlet valve may be open and admitting compressed air to the cylinder at the time the trip device is operated. Thus the breaker is trip free of the closing means.

The compressed air operating means is operable to produce normal closing operations of the circuit breaker starting from the full open position of the breaker, and is also operable to eiect quick automatic reclosing operations of the breaker vwherein the reclosing movement is initiated at an intermediate point in the opening stroke of the breaker after the circuit is interrupted but before the breaker reaches full open position. The control circuits for controlling the operation of the inlet valve electromagnet I1 and the trip device 8l are preferably the same as the control circuits disclosed in the aforementioned Patent No. 2,408,199. These control circuits have not been shown in this application as they are unnecessary for a complete understanding of the present invention. It is believed suicient to state that the tripping electromagnet 8| is energized in response to an overload or short circuit in the main circuit, and also by a manual trip control switch. For quick automatic reclosing operations, the inlet valve controlling electromagnet is automatically energized by an auxiliary switch at an intermediate point in the opening stroke of the breaker to cause the inlet valve to admit compressed air to the operating cylinder at this time. The auxiliary switch is adjustable so that regular automatic reclosing operation from the full open position may be obtained if desired. The electromagnet ||1 may also be energized by a manual closing control switch to effect closing operation of the circuit breaker from the full open position of the breaker.

An automatic throttle device is provided which is effective to throttle the flow of compressed air to the operating cylinder a predetermined amount during the rst part of the closing stroke of the operating piston on closing operation of the circuit breaker started from the full open positionl and which is automatically operated to an open or non-throttling position during the latter portion of the closing stroke to permit compressed air to flow to the operating cylinder at an increased rate during the iinal portion of the closing stroke. Compressed air is admitted relatively slowly by the throttle during the rst part of the closing operation, thus decreasing the tendency of the operating mechanism to slam. A larger quantity of compressed air is admitted to the operating cylinder by the throttle during the nal portion of the closing stroke thereby providing sufficient driving power to overcome the relatively heavy contact load imposed by the contact pressure spring means during the nal portion of the closing stroke. The throttle means is also constructed so that it will remain in Wide open position during the major portion of the opening stroke of the operating piston and during quick reclosing operations, thereby admitting the larger quantity of compressed air necessary to quickly reverse the movement of the circuit breaker and quickly reclose the same.

The automatic throttle means comprises a gate valve element |3| slidably mounted in a vertically disposed recess |33 which crosses the inlet air passage |I2 in the inlet valve housing ||9. A closure cap |35 is secured in the upper end of the recess |33 for closing the upper end of this recess. The valve element I3| is mounted on a rod |31 which slidably extends in a fluid-tight manner through an opening provided therefor in the closure member |35. The upper end of the rod |31 is threadedly connected to a U-shaped connecting element |39, a lock nut |4I being provided to secure the connection. 'Ihe valve element |3| is adapted to be actuated to a throttling position by a snap-acting spring toggle mechanism indicated generally at |42 and comprising a pair of rods or links |43 and |45 having U- shaped rod ends |41 which are pivotally connected together and to the connecting element |39, by a pivot pin |49 which forms the knee of the actuating toggle. The free ends of the toggle rods |43 and |45 slidably extend through enlarged openings provided therefore in a pair of supporting arms which are secured to the closure member |35. A compression spring |53 is mounted on each toggle rod and disposed in com- .pression between the rod head |41 and supporting arm |5| ofthe rod.

The valve element |3| is adapted to be actuated to its throttling position shown in Fig. 1 during the latter part of the opening stroke of the breaker and operating piston, and actuated downwardly to its open or non-throttling position during the latter portion oi the closing stroke of the breaker operating piston. A link |55 is provided for 'the purpose of initiating the actuation of the valve element |3| at the proper time. The connecting link |55 is pivotally connected at its lower end to the knee of the actuating toggle by means of the pivot pin |49, and the upper portion of the link is provided with an elongated slot |51 which engages a pin or stud |59 projecting laterally from the breaker operating lever 35. An adjusting screw |5| is threaded into the upper end oi' the link |55 and the lower end of this screw is adapted to extend into the upper portion of the slot |51. The adjustment of the screw |5| determines the point in the opening stroke of the breaker operating piston at which actuation of the valve element |3| to its throttling position will be initiated, An adjustable collar may be mounted on the link |55 adjacent the lower end of the slot |51 to determine the point at which actuation of the valve element |3| to its open position will be initiated.

The inlet air passage |2 is of general triangular shape, as shown in Fig. 2, so as to provide for a maximum range of adjustment of the throttle opening provided by the valve element |3| in the throttle position thereof. In the position of the parts shown in Figs. 1 and 2, the valve element |3| provides a relatively high degree of throttl-ing since only the apex of the triangular shaped inlet passage |2 is uncovered by the valve element in the throttling position thereof.

rEhe operation of the mechanism is briei'ly as follows: When the circuit breaker is in the full open position, as shown in Fig. l, the throttle valve element |3| is maintained in the throttling position as shown, in which it will act to throttle the ilow of compressed air to the upper end of the cylinder a predetermined amount. To close the circuit breaker, the inlet valve controlling electromagnet ||1 is energized. Energization of the electromagnet ||1 opens the pilot valve ||5 and thereby causes opening of the main inlet valve |2|. Upon opening oi the main inlet valve |2| compressed air ows through the inlet passage I2 into the upper end of the operating cylinder 25 and moves the operating piston |03 downwardiy to closed position to effect closing of the circuit breaker. During the first part of the closing stroke, the throttle valve |3| is maintained in throttling position in which it throttles the flow of compressed air to the cylinder a predetermined amount admitting air to the operating cylinder' relatively slowly. Shortly before the contacts of the circuit breaker touch, the projecting pin 5.@ will engage the bottom of the slot |51 in the link |55 and thereby initiate actuav.tion of the throttle valve |3| to its open position.

As soon as the knee pin |69 of the actuating toggle is moved downwardly through the dead-center position, the spring toggle actuates the valve element |3| downwardly to its open position with a snap action, thus the valve element |3| is actuated to open throttle position during the latter portion of the closing stroke of the breaker operating piston and allows the compressed air to now at an increased rate into the operating cylinder and thereby provide a relatively large driving force during the nal portion of the closing stroke of the operating piston. When the circuit breaker reaches the fully closed position, the latching roller 41 is engaged under the main latch 5| and the breaker is held latch closed by the latching mechanism. As soon as the breaker reaches the fully closed position, the valve controlling electromagnet |1 is deenergized and the main inlet valve |2| returns to closed position shutting off the flow of compressed air to the operating cylinder 29.

If an overload or short circuit occurs in the circuit controlled by the circuit breaker, the trip device 8| will be immediately energized and the trip plunger 19 thereof quickly moved upwardly to effect release of the latching mechanism and at the same time opening of the exhaust pilot valve |25. The release or the latching mechanism comprising the auxiliary latch 51 and main latch 5| permits the circuit breaker to be moved quickly to open position by its accelerating spring I5. The opening of the exhaust pilot valve will cause the main exhaust valve to open if there is any substantial air pressure in the operating cylinder above the piston |33, to thereby dump the air to atmosphere through the exhaust ports |23.

If the circuit breaker is set for quick automatic reclosing operation, the inlet valve controlling electromagnet |1 will be automatically energized early in the opening stroke of the circuit breaker thereby causing the inlet valve |2| to open and admit compressed air to the operating cylinder during the opening movement. The throttle valve |3| remains in the open or non-throttling position during the major portion of the opening stroke and hence will be in open position at the time compressed air is admitted for quick reclosing and will remain open during the `quick reclosing operation. This is due to the length of the slot |51 in the connecting link |55. Since the throttle valve 3| is in the open throttle position a large quantity of compressed air will be admitted to the operating cylinder and the compressed air will quickly reverse the movement of the operating piston and initiate the reclosing movement of the operating piston at an intermediate point in the opening stroke before the circuit breaker reaches full open position. The reclosing movement proceeds and if the fault or overload condition which caused the initial opening has been cleared, the circuit breaker will be driven to the fully closed position and relatched. The inlet valve controlling electromagnet |1 will be deenergized and the inlet valve |2| returned to closed position when the breaker reaches the fully closed and latched position. However, if the overload or fault condition is still present at the time the circuit breaker contacts reach the touch position during the reclosing movement, the trip device 8| will be immediately energized in response to the overload condition and will retrip the breaker by releasing the latching mechanism and simultaneously opening the exhaust pilot valve |25. The opening of the exhaust pilot valve |25 will cause the main exhaust valve to open and dump the closing air from the operating cylinder to atmosphere so that it will not retard i the opening movement of the circuit breaker.

The circuitA breaker may be manually tripped by means of the manual trip control switch which effects energization of the trip device 8|. The circuit breaker will be moved quickly to the full open circuit position and during the latter part of the opening movement shortly before the breaker reaches its full open position, the projecting pin I 59 on the breaker operating lever 35 will engage the adjusting screw |6| adjacent the end of the slot |51 and initiate the actuation of the throttle valve element I3I to its throttling posiion shown in Fig. 1. The snap action toggle will thereby be caused to move to its upper overcenter position shown moving the valve with a snap action to its throttling position. The mechanism is now ready for a normal closing operation.

From the foregoing, it will be seen that the automatic throttle valve |3I causes the flow of compressed air to the operating cylinder to be throttled a predetermined amount during the rst part of each closing operation started from full open position, and the throttle valve is automatically opened during the latter part of the closing stroke of the operating piston thereby admitting a large quantity of air to the upper side of the operating piston during the final portion of the closing stroke. The throttle valve remains in the open throttle position during the major portion of the opening stroke of the operating piston and during quick reclosing operations, due to the elongated slot |51 in the connecting link |55, so that an increased quantity of air will be admitted to the operating cylinder on quick reclosing operations. 1

The pressure in the storage tank I I I is reduced by each closing operation of the breaker and, when several closing operations occur in a short interval of time, the pressure in the storage tank may be reduced to the point (approximately 80% of normal) where the compressor unit is unable to maintain the pressure at the normal level. High ambient temperatures may raise the pressure in the storage tank to approximately 110% of normal. Also, pressure relief valves used on compressed air storage systems for circuit breakers of this type disclosed are usually set to function at approximately 115% of normal pressure. Consequently, the operating mechanism may be required to operate at air pressures ranging from approximately 80% to 115% of normal pressure.y As previously set forth, operation of the circuit breaker with abnormal or subnormal air` pressure may cause damage to the breaker.

In accordance with the present invention, means is provided which is at all times operable in response to the pressure of the air in the reservoir to vary the size of the inlet passage ||2 according to the variation of the pressure in the reservoir.

Referring to the drawings, the pressure responsive device comprises an expandable and contractable metal bellows I1I disposed in a cylindri.- cal recess |13 in the bottom of the valve housing IIS. The bellows is secured to the upper wall of the recess |13 and the bottom of the recess is closed by means of a plate |15 secured to the valve housing II9. The lower end of the bellows |1| is secured to a disc |11 which may be either secured to or formed integral with an upwardly extending valve rod |19 on the upper end of which is secured a gate valve |8I. The valve I8I is disposed in the recess |33 adjacent the valve I 3|- (see Fig. l) and across the inlet passage II2.-v

The space |13 surrounding the bellows I1| is connected by means of a conduit |83 to the sup-l 10 ply reservoir III so that the space |13 is at all times responsive to the pressure of the compressed air in the reservoir III. A coil spring |85 disposed inside the bellows I'II and surrounding the valve rod |19 biases the bellows I1I to its extended position and biases the valve ISI toward its open position against the pressure in the space E13 which is maintained at the pressure in the reservoir I I. When the pressure in the reservoir III increases above normal the bellows |1I "contracts proportionately and moves Ithe valve iti upwardly to decrease the throttle opening in the inlet passage I I2. When the pressure in the reservoir decreases, the spring expands the bellows III and moves the valve ISI downwardly to increase the throttle opening in the inlet passage IIZ. Thus the size of the throttle opening is at all times inversely adjusted in relation to the pressure of the compressed air in the reservoir l I I. That is, when the pressure in the reservoir increases the size oi the throttle opening decreases proportionately and when the pressure in the reservoir decreases the size of the throttle opening increases proportionately. It will be noted that the variation of the size of the throttle opening in response to the pressure in the reservoir is entirely independent of the mechanically operated throttle valve I3 I. As a result, the speed of operation oi the mechanism is maintained substantially constant irrespective of the variations in the available air pressure above or below normal pressure. I

By operating independently of the automatic throttle valve I3Iy the pressure responsive throttle valve ISI provides control of the amount of compressed gas admitted to the operating mechanism near the end of a closing stroke when the throttle valve I3I is mechanically opened, In other words, if the pressure in the reservoir is excessive the throttle valve |8| will reduce the size of the throttle opening irrespective of the opening of the automatic throttle valve I3I near the end of the closing stroke of the breaker. In prior art devices, the throttle valve was fully opened near the end of the closing stroke irrespective of the pressure of the compressed air in the compressed air supply tank.

According to the modification of the invention shown in Fig. 4 of the drawings, a single throttle valve is provided that is controlled by the position4 of the breaker mechanism and at all times is controlled by the pressure in the supply reservoir.

In the Fig. 4 modification, a piston type throttle valve |81 is disposed in a cylindrical opening |89 formed in an inlet valve housing ISI across the inlet passage II2. The housing I9I is also provided with an opening |93 in which is disposed a metal bellows |95 similar to the metal bellows I1I of the Fig. 1 modication but which is disposed to one side of the throttle valve rather than in substantial axial alignment therewith. The throttle valve |81 is secured to a valve rod |91 which extends upwardly through a huid-light opening in the housing |9| and which is pivotally connected at I 99 to a lever 20| at a point between the ends thereof.

The bellows |95 is secured to the upper wall of f ai." 239 to one end of the lever 20|.` 'Ifhe opposite end of the lever 20| is pivotally connected at 2| I to the lower end of a rod 2|3 having its upper end operatively connected to the toggle mechanism |42 (Fig. 1) the rod 2I3 replacing the valve rod |31 and being connected to the toggle mechanism in the same manner.

The space |93 surrounding the bellows |95 is connected by means of the conduit |83 to the supply reservoir (Fig. 1) so that the space |93 is at all times maintained at the pressure in the reservoir and is at all times responsive to changes in pressure in the reservoir. A coil spring 2|5 (Fig. 4) disposed inside the bellows |95 and surrounding the rod '201 biases the bellows to its extended position against the pressure in the space |93 which varies according to variations of pressure in the reservoir When the pressure in the reservoir increases above normal pressure the bellows |95 contracts proportionately and moves the rod 2231 upwardly. This movement of the rod 2(11 causes the lever 20| to move counterclockwise about the pivot 2| and, acting, through the Valve rod |91, moves the throttle valve |81 upwardly to decrease the throttle opening in the inlet passage I2. When the pressure in the reservoir decreases, the spring 2|5 expands the bellows |95 and rotates the lever 20| clockwise thereby moving the throttle valve |81 downwardly to increase the throttle opening in the inlet passage |l2. Thus the size of the throttle opening is at all times inversely adjusted in relation to the pressure in the reservoir III irrespective of the position of the circuit breaker mechanism.

The throttle valve device is shown in Fig. 4 in the open position of the circuit breaker wherein the throttle opening is substantially closed ofi in order to decrease the amount of compressed air admitted to the cylinder at the beginning of the closing stroke. It will be obvious that the position assumed by the throttle valve in the open position of the breaker will be varied according to the pressure in the reservoir During the closing operation of the breaker the rod 2|3 is actuated downwardly by the toggle mechanism |42 in the previously described manner to move the throttle valve |81 to the open position to thereby increase the amount of compressed air admitted to the operating cylinder at approximately the time the contacts touch. It will also be obvious that the open position of the throttle valve will be varied. according to the pressure in the reservoir Thus, irrespective of variations above or below normal of the available air' pressure. the speed of operation of the mechanism is substantially constant.

While the invention has been disclosed in accordance with the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts may be made without departing from some of the essential features of the invention.

I claim as my invention:

1. A circuit breaker comprising compressed gas operating mechanism for operating said circuit breaker, a gas pressure supply system including a main storage tank for supplying compressed gas to actuate said operating mechanism, means including a iirst gate valve for controlling the rate of flow of compressed gas to said operating mechanism, actuating means for said gate valve controlled in response to predetermined movement of said breaker, means including a second gate valve disposed in physical engagement with but movable independently of said first gate valve, said valves cooperating to formx a variable orifice for controlling the rate of iiow of compressed gas to said operating mechanism, and means including a metal bellows responsive to changes in gas pressure in said main storage tank only for at all times controlling the position of said second gate valve and conduit means communicating said metal bellows directly with said main storage tank.

2. A circuit breaker operating means of the compressed gas type comprising a cylinder, a piston in said cylinder for operating the breaker, a source of gas under pressure including a main storage tank for supplying compressed gasto aotuate said piston, means including a first valve for controlling the rate of flow of compressed gas to said cylinder, actuating means for said valve controlled in response to predetermined movements of said breaker, a second valve disposed in physical contact with but movable inded pendently of said rst valve to form a variable orifice for controlling the rate oi flow of compressed gas to said cylinder, means movable in response to changes in the gas pressure in said main storage tank for at all times controlling the position of said second valve, and a pipe communicating said pressure responsive means directly with said main storage tank.

3. A circuit breaker comprising compressed iiuid operating mechanism for operating said circuit breaker, a source of supply of iluid under pressure comprising a main storage tank, an inlet passage for admitting fluid pressure to said operating mechanism, a first valve means disposed in said inlet passage for controlling lthe rate of flow of compressed fluid to said operating mechanism, actuating means for said rate control valve operable in response to predetermined movement of said circuit breaker, a second valve means disposed in said inlet passage in sliding contact with said iirst valve to denne a Variable orifice and operable independently of said circuit breaker for controlling the rate of now of com-I pressed fluid to said operating mechanism, and pressure responsive means including a metal bellows attached to said second valve means and operable in response to variations of pressure in said main storage tank to at all times vary the rate of flow of compressed fluid to said operating mechanism, and means communicating said metal bellows directly with said main stord age tank.

4f. A circuit breaker comprising a iluid motor' operated operating mechanism for operating said circuit breaker, a source or fluid under pressure including a main storage tank, an inlet passage communicating said source to said fluid motori a pair of independently movable gate valves disposed in sliding contact with each other to define a single variable orifice in said inlet passage for controlling the rate of iiow of fluid pressure to said motor, separate actuating means for each of said valves, each of said actuating means being responsive to different conditions to actuate its associated valve to vary the size of said variable orifice and the rate oi flow of fluid presssure to said motor and a conduit communieating the other of said actuating means directly with said main storage tank.

5. A circuit breaker comprising compressedv gas operating means for operating said circuitf breaker, a gas pressure supply system including a main storage tank; an inlet valve for admitting a.

charge; of compressed gas to said operating means, a irst conduit communicating said inletvalve with said main storage tank, an inlet pas-` sage communicating said. inlet valve with saidoperating means, a rst gate valve disposed in said inlet passage, means operable by said circuit breaker for positioning said first gate valve in response to predetermined movements of said breaker, a second gate valve disposed in said inlet passage and cooperating with said first gate valve to define a variable orifice for varying the rate of flow of said charge of compressed gas to said operating means, pressure responsive means for positioning said second gate valve, and a second conduit communicating said pressure responsive means with said main storage tank independently of said rst conduit so that said second gate valve is positioned at all times in accordance with the pressure in said main storage tank.

6. A circuit breaker comprising compressed gas operating means for operating said circuit breaker, a gas pressure supply system including a main storage tank, an inlet valve operable to admit a charge of compressed gas to said operating means, a rst conduit communicating said inlet valve with said main storage tank, an inlet passage communicating said inlet valve with said operating means, a rst valve disposed in said inlet passage, a second valve disposed in said inletl passage in sliding engagement with said first valve, said rst and second valves forming a single variable orifice for controlling the rate of iiow of said charge of compressed gas to said operating means, means operable by said operating means ior positioning said first valve according to the position of said breaker, pressure responsive means for positioning said second valve, and a second conduit communicating said pressure responsive means directly with said main storage tank so that said second Valve is positioned at all times in accordance with the pressure in said main storage tank irrespective of the position of said breaker.

7. A circuit breaker biased open and having a fluid motor operated mechanism for closing said circuit breaker, a uid pressure supply system including a main storage tank, inlet valve means operable to admit a p-redetermined charge of fluid under pressure to said fluid motor to actuate said operating mechanism, a rst conduit connecting said main storage tank directly to said inlet valve means, an inlet passage communicating said inlet valve means with said fluid motor, means defining a variable orifice in said inlet passage, means operable according to the position oi" said circuit breaker for varying the flow area of said variable orice means, pressure responsive means at all times connected to said throttling valve means and responsive solely to the pressure in said main storage tank for varying the flow area of said variable orifice means in both the open and closed positions of said breaker, and a second conduit communicating said pressure responsive means directly with said main storage tank so as to vary the flow area of said variable orice means in all positions of said breaker in accordance with the pressure in said main storage tank.

8. A circuit breaker biased to an open position, operating means including a cylinder having a p-iston movable therein for operating said breaker to a closed position, a source of fluid under pressure including a main storage tank, inlet valve means operable to admit a predetermined charge of fluid under pressure to said cylinder, rst conduit means communicating said storage tank to said inlet valve means, an

inlet passage communicating said inlet valve means to said cylinder, throttling valve means interposed in said inlet passage for controlling the rate of flow of said charge oi fluid to said cylinder, actuating means for said throttling valve means controlled in response to movement of said breaker to the open and closed positions to move said throttle valve means between two positions to thereby vary the flow of said charge of fluid to said cylinder according to the movement of said breaker, fluid pressure responsive means at all times connected to said throttling valve means and responsive solely to uid pressure in said main storage tank to vary the position of said throttling Valve means in both the open and closed positions of said breaker and at all times according to variations of pressure in said main storage tank, and a second conduit means communicating said pressure responsive means to said main storage tank separate from said first conduit means so that said pressure responsive means at all times is responsive to the pressure in said main storage tank.

9. A circuit breaker biased to an open position, compressed gas operating mechanism for operating said circuit breaker to a closed position, a gas pressure supply system including a main storage tank, inlet valve means operable to admit a charge of compressed gas to said cylinder, a conduit directly communicating said storage tank to said inlet valve, an inlet passage communicating said inlet valve means to said cylinder, valve means in said inlet passage for varying the flow area of said inlet passage, means responsive to movement of said breaker to the open and closed positions to automatically adjust said valve means to two positions to vary the flow area of said orifice according to the movement of the breaker, pressure responsive means at all times connected to said throttling valve means for adjusting said throttling valve means in both the open and closed positions of said breaker according to the pressure in said main storage tank, and a separate conduit directly communicating said pressure responsive means directly to said main storage tank so that said pressure responsive means is at all times responsive to the pressure in said main storage tank.

DOUGLAS J. MARSDEN.

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

UNITED STATES PATENTS Number Name Date 308,030 Collis Nov. 11, 1884 2,379,178 Peek June 26, 1945 2,381,307 Peek et a1. Aug. 7, 1945

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