US3383853A - Energy storage mechanism for actuating circuit breakers and the like - Google Patents

Description

y 1968 E. 1. ENGEL ETAL 3,383,853

ENERGY STORAGE MECHANISM FOR ACTUATING CIRCUIT BREAKERS AND THE LIKE Filed May 17, 1966 2 Sheets-Sheet 1 FIG.

POWER SOURCE HYDRAULIC FLUID 7 RESERVOIR #4 SLOW CLOSE CONTROL IN VEN TORS.

EDWARD l. ENGEL W. JORDAN SMITH ATTORNEY y 1968 E. ENGEL ETAL 3,383,853

ENERGY STORAGE MECHANISM FOR ACTUATING CIRCUIT BREAKERS AND THE LIKE Filed May 17, 1966 2 Sheets-Sheet Ill/Ill a 1mm INVENTORS EDWARD |..ENGEL W. JORDAN SMITH 131w fw ATTORNEY United States Patent ENERGY STORAGE MECHANISM FOR ACTUAT- ING ClRCUlT BREAKERS AND THE LlKE Edward I. Engel, Matawan, N..l., and William J. Smith, McMurray, Pa., assigncrs to Federal Pacific Electric Company, Newark, N.J., a corporation of Delaware Filed May 17, 1966, Ser. No. 550,830 7 Claims. (Cl. 6tl-7) ABSTRACT 9F THE DISCLOSURE Energy storage mechanism for actuating circu't brealr ers and the like utilizing a hydraulic system for charging an energy storage spring with selectively controlled release of the energy stored in the spring.

This invention relates to energy storage mechanisms and more particularly to an energy storage mechanism for actuating circuit breakers and the like.

Th use of stored energy mechanism for actuating circuit breakers and the like is Well known in the art. Many mechanisms of various types and degrees of sophistication have been suggested and have met with varying success. The basic requirement of all such mechanisms is the ability to store small amounts of energy, available over a relatively long period of time, and to deliver the stored energy in a relatively short period of time. Where, as in circuit breakers for use at 600 volts and less, a small amount of stored energy was required, mechanical means utilizing a motor driven pawl and ratchet arrangement have been successfully employed. Such a construction is illustrated in Patent No. 3,097,275 entitled Circuit Interrupters which is assgned to the same assignce as the present invention. However, wherein considerably larger amounts of stored energy were required, as for closing circuit breakers in the to kilovolt service range, the art turned to the use of hydraulic or hydropneumatic accumulators. in such hydraulic mechanisms the hydraulic iiuid system is pressurized and is used either directly or indirectly to cause operation of the circuit breaker. A piston of the hydraulic system is directly connected to the operating linkage of the circuit breal er in the direct mechanism and the fluid pressure in the system operates the breaker; in the indirect system a stored energy spring is charged by the hydraulic system and the stored energy is subsequently used to operate the breaker linkage. An object of this invention is to provide an improved, novel, and simplifled iydraulic system for operating circuit breakers and the like.

Another object of this invention is to provide a hydraulic system for charging a stored energy spring including a hydraulic pumping system having novel means for controlling the delivery of the fiuid pressure from the pumping system to the energy storage spring.

Yet another object of this invention is to provide a storage energy operating mechanism for charging the operating spring of a circuit breaker wherein the discharge of the energy stored in the spring may proceed at an unimpeded rate or, selectively may be inhibited to provide slow speed closing of the associated circuit breaker. It will be seen from the discussion below that this is particularly advantageous for multi-pole circuit breakers so that the closing sequence of the current carrying and arcing contacts can be adjusted. The ability to completely stop the breaker at any point in its closing motion is also advantageous in checking the proper function of various circuit breaker components.

The above and other objects and advantages of the invention are accomplished in one embodiment of the ice invention wherein an energy storage mechanism is provided which includes an energy storage spring having a one-way driving connection to the circuit breaker, means for charging the spring to store the energy require-d for closing the circuit breaker and means for releasably latching the spring in its charged condition. The means for charging the spring includes a hydraulic jack connected to the spring and a motor driven two-stage hydraulic pressurlzing system having a low pressure pump and a high pressure pump. Control means are provided responsive to the presence of the low pressure of the pressurizing system while the pumps are operating to control the de livery of hydraulic fluid by the high pressure portion of the system to the spring charging jack and to provide controlled release of the energy stored in the spring when said pumps are not operating.

The nature of the invention and its various further as poets and features of novelty will be appreciated from the illustrative disclosure that is given in detail below, and from the accompanying drawings which form p r of this disclosure.

In the drawings:

FIG. 1 is a diagrammatic representation of an embodiment of the invention, associated with a circuit breaker, in which the energy storage mechanism is shown at the start of the charging cycle and the circuit breaker is shown closed; and

FIG. 2 is a similar view in which the energy storage mechanism is shown in its fully charged condition and the circuit breaker is open and ready to be closed.

Referring to the drawings, the stored energy mechanism 10 comprising a multi-stage hydraulic pressurizing systom 12 and an energy storage system 14 is illustrated in assocation with a circuit breaker 16. A similar circuit breaker having the same linkage system but which employs a solenoid type closing mechanism is shown and described in detail in US. Patent No. 2,943,168 which is assigned to the assignee of the present invention. Circuit breaker 16 is multi-pole and has a plurality of contact pairs 18 which close under drive impetus supplied, in the present invention, by the stored energy mechanism it The linkage of the circuit breaker includes a driving member 2% operatively connected to the stored energy mechanism 10, a driven member 22 connected to the movable contacts and a controlled latch 24 coupling the driving and driven members to each other in a trip-free rela ionship. The controlled latch 24 is engaged by a prop 26 to hold the operating mechanism closed. Further discussion of the circuit breaker mechanism is not elieved to be necessary to the understanding of the present invention and will therefore be omitted in the interest of brevit The energy storage system 14 is mounted on the frame of the circuit breaker and includes a hydraulic jack 27 which has its housing 28 secured to the frame. A spring carriage 30 is mounted on a pair of rods 32 attached to the frame for reciprocating movement therealong. Carriage 30 is connected to driving member by a pair of spaced links 33 (only one shown) that straddle the jack housing and pass through appropriate apertures in the frame. A heavy coil spring 34 is constrained between the carriage and a retainer cap 36 secured to the remote ends of the rods 32. An overcentering toggle 38 is provided for releasably restraining the carriage 30 in the charged condition of spring 34 (FIG. 2). Toggle 38, which is positioned within the volume defined by the coil spring 34, cap 36 and cylinder member 28 is comprised of two links, 46 and 42, which are connected at a knee 44. Link 40 is pivoted at 46 to the carriage 30 and link 42 is pivoted on shaft 48 which is supported by plates 49 attached to rods 32 (only one shown). As carriage 30 moves toward end cap 36 during the process of charging the spring, as

will be explained in greater detail below, the knee 44 of the toggle moves counterclockwise about pivot 48. Shortly after the knee 44 passes overcenter (FIG. 2) an adjustment pin carried by link 40 engages a stop 52 carried by plates 49 and arrests further movement of the knee in the charging direction. Simultaneously a second pin 54 actuates a switch 56. A rotatable cam mechanism 58, is provided for shifting the toggle overcenter from the position shown in FIG. 2 when the energy previously stored in the spring 4 is to be released. The toggle arrangement 38 and the release mechanism 58 are shown and described in greater detail in copending application Ser. No. 567,960, filed July 26, 1966, which is assigned to the same assignee as the present invention.

Jack housing 28 has a central bore or cylinder with a single port 62. Port 62 is connected by hydraulic line or passageway 64 to the hydraulic fluid pressurizing system 12. A piston member or ram 66 is secured at one end to the spring carriage 30 and is slidable in the bore 60. Seal 68 on the ram engages the inner surfaces of the bore and retains the hydraulic fluid.

The hydraulic fluid pressurizing system 12 includes a two-stage pumping system comprising a relatively low pressure (for example, 300 psi.) gear pump 70 and a relatively high pressure (for example, 4000 psi.) piston pump 72 that are connected by shaft 73 to the same electric dirve motor 74 for simultaneous operation. Well known relatively incompressible hydraulic oil is used as the force transmitting medium in the preferred embodiment of the invention. Control valve 76 is used to control the delivery of high pressure fluid from piston pump '72 to the jack 27 and, as will be explained below, selectively controls the egress of the fluid from the jack during the breaker closing operation. The valve housing 78 contains a movable piston 80 which separates portions of the bore 82 to form two chambers, i.e., vented chamber 84 and low pressure chamber 86. The piston 80 has a broad face 80a forming one wall of the low pressure chamber 86 and has an oppositely disposed face 80b in the vented chamber 84. Face 8011 carries a ball valve member 88a. Ball valve member 88a cooperates with a wall mounted valve seat 88b to form valve 88 which is able to selectively close off high pressure port 90 that communicates with the conduit 64 that connects the pressurizing system 12 and jack 27. A second port 92 in the vented chamber 84 connects the valve to the hydraulic fluid reservoir 94 through passageway or conduit 96. A high pressure relief valve 98 vents conduit 64 to the reservoir 94 through conduit 96.

Gear pump 70 draws hydraulic fluid from the reservoir 94 through conduit 100. The low pressure fluid from gear pump 70 is driven through conduit 102 to the input of the piston pump 72. Check valves 104, are positioned in conduits 102 and 64, respectively. Valve 104- prevents return flow during pumping and valve 105 prevents return flow during pumping and when the piston pump is not driven by motor 74. Branch conduit 104 connects conduit 102, between the check valve 106 and the gear pump 70, to the low pressure chamber 86 of the control valve through port 108. Bypass valve 110 vents conduit 106 to the reservoir 94 through conduit 100 in the event that excessive pressure should appear in conduit 106.

Control valve 76 is provided with means for selectively controlling the position of floating piston 80. The positioning means includes a longitudinally extending shaft 112 which has an end adapted to engage the low pressure face 80a of the piston. The position of shaft 112 in the valve body 7 8 is adjusted by a slow close control member 114 that threadedly engages the housing. Escape of hydraulic fluid from the housing is prevented by a O-ring seal 116 on shaft 112. Shaft 112 may be driven against the piston 80 by the control member 114 to so position the piston that ball valve 88 will effectively close the port '90 thus preventing fluid from conduit 64 from entering the chamber 84 in the valve. By adjustment of the slow close control member 114 the valve 88 may be opened At slightly to permit controlled flow of fluid through the port 90.

The electric drive motor 74 is connectable to source 111 of electrical energy by the operation of a relay 120 which has contacts 120a and 12011 operatively connected thereto. Switch 56 that is operated by pin 50 on toggle 38 and a second switch 122, which is mounted on the breaker frame and which is operated by a portion of the controlled latch 24, are connected in series with the relay 120.

For a more thorough understanding of the invention the operation of the energy storage mechanism will now be explained in detail. Referring to FIG. 1, energy storage spring 34 is shown fully extended at the start of the charging cycle just after a breaker closing operation. As the breaker mechanism assumed its closed circuit posi tion the control latch 24 closed the normally open switch 122, completing the circuit through switch 56 thus causing relay 120 to be energized. Normally open relay con tacts 120a and 12012 are now closed. Contacts 120a maintain the circuit to the relay while contacts 1201) connect the motor 74 to the power source 118. Motor 74 is energized driving gear pump 70 and piston pump 72. Low pressure gear pump 70 pumps hydraulic fluid from the reservoir 94 to the piston pump 72 through check valve 104 and to the low pressure chamber 86 of the control valve 76 through conduit 102. Hydraulic fluid at high pressure is forced by the piston pump through check valve 105 into passageway or conduit 64 and transmitted thereby to the jack 27. Flow of the high pressure fluid into the control valve 76 is prevented by ball valve 88 which is automatically closed by the low pressure fluid operating on the large face 80a of piston 80. The force produced on the large area of the low pressure side of the piston is greater than that produced on the small surface at the high pressure side thereby assuring a tight seal at port 90. The hydraulic fluid present in the vented chamber 84 at the start of the cycle is vented through port 92 to the reservoir 94 by the movement of the piston 80 and does not retard its movement. The fluid pressurization described causes the hydraulic jack 27 to extend ram 60 moving spring carriage 30 toward the end cap 36 thereby charging the spring 34. The one-way driving connection between the stored energy mechanism and the breaker, which includes driving member 20 and controlled latch 24-, allows the spring 34 to be charged without disturbing the breaker. As the carriage 30 withdraws the driving member 20 is retracted leaving the controlled latchv 24 in engagement with the prop 26 which maintains circuit breaker closed. Equipment constructed according to the present invention has a charging time of three seconds. When the spring 34 is fully charged (FIG. 2) toggle 38 is overcentered and pin 50 opens switch 56 thereby opening the circuit to motor 74. The de-energization of the motor automatically relieves the pressure in both the high and low pressure portions of the system 12 since it is the presence of low pressure fluid in valve chamber 86 that seals off the high pressure system. The pressure is relieved by clearance provided in the low pressure gear pump. The stored energy mechanism 10 is now ready for the next closing operation of the breaker. (The breaker is opened by the release of the controlled latch member 24- (see Patent No. 3,097,275) at which time the breaker parts assume the position shown in FIG. 2.)

The breaker closing operation is initiated by the release mechanism 58 which lifts the knee of the toggle 44 overcenter. When the toggle 38 overcenters, the energy stored in the spring 34 is available to drive carriage 30, and through links 33, drive the member 20 in a closing stroke toward the position shown in FIG. 1. The discharge time is approximately .02 second. The hydraulic fluid present in the jack 27 is vented to the reservoir 94 through the control valve 76 since the path through the piston pump 72 is blocked by check valve 105. In the absence of low pressure on piston 80 it is shiftable to a position of clearance by the force generated by the fluid being vented from the jack through conduit 64. Port 90 is opened by the movement of the piston and fluid from the jack is then able to flow through valve 76 and through port 92 to conduit 96 to the reservoir 94. Fluid in the low pressure chamber 86 of the valve is displaced by the movement of piston 80 back through the conduit 106 and through the gear pump 70 to the reservoir 94. Bypass valve 110 allows the displaced fluid to bypass the gear pump in the event that a pressure buildup occurs in the gear pump 70. Normally, the small amount of fluid in the low pressure chamber is able topass through the gear pump with case.

In the foregoing, the discharge of the spring 34 and the closing operation of the breaker 16 is unimpeded by the control valve 76. If controlled closing of the breaker is desired, piston 80' may be held in the port 90 blocking position to thereby prevent or control escape of the fluid from the piston. In this case although the spring 34 has been released by the toggle 38, which has been moving overcenter by operating mechanism 58, the breaker will not close nor will the energy stored in the spring 34 be discharged. Piston 80 is held in the port blocking position by the shaft 112 which is driven against it by the slow close control 114. Gradual closing of the breaker may be achieved by allowing slow flow of fluid through the port 90 past the ball valve 88. This is accomplished by operating the slow close control 114 to allow piston 80 to shift thereby allowing the venting of the oil from the conduit 64 and the hydraulic jack 27. Check valve 105 and excess pressure relief valve 98 assure that the jack fluid can vent only through the control valve 76. Relief valve 98 prevents dangerous excess pressures from occurring during the closing operation as well as during the charging operation. In this mode of operation control valve 76 may be utilized to stop the breaker mechanism at any point in the closing stroke so that the closing sequence of the contacts 18 may be studied and adjusted.

It will be noted from the foregoing that in the normal operation of the system the fluid pressure used to charge spring 34 is released automatically, when the spring is fully charged by the cessation of operation of motor 74, without reliance on any mechanism other than the presence or absence of low pressure generated by the operation of the gear pump.

While only one embodiment of the invention has been shown and described herein, it will be obvious to those skilled in the art that various modifications and changes may be made herein without departing from the spirit and scope of the invention.

What is claimed is:

1. An energy storage mechanism for actuating circuit breakers and the like including a spring having a one-way driving connection to the circuit breaker, means for charging said spring to store therein the energy required for closing the circuit breaker, and means for releasably latching said spring in its charged condition, said means for charging said spring including a two-stage hydraulic fluid pressurizing system including a low pressure pump and a high pressure pump, a hydraulic jack operatively connected to one end of said spring and control means responsive to the operation of said low pressure portion of said pressurizing system for controlling the delivery of high pressure hydraulic fluid from said high pressure pump to said spring charging jack, said control means providing selectively controllable release of the energy stored in said charged spring in the absence of said low pressure.

2. An energy storage mechanism according to claim 1 wherein said control means is a valve member having opposed chambers operatively connected to said high and low pressure pumps respectively, a piston in said valve shiftable in response to fluid pressure to a high pressure releasing position and means for selectively preventing the movement of said piston to said high pressure releasing position.

3. An energy storage mechanism for actuating circuit breakers and the like including a spring having a one-way driving connection to the circuit breaker, means for charging said spring to store therein the energy required for closing the circuit breaker, means for releasably latching said spring in its charged condition, said means for charging said spring including a hydraulic jack connected to one end of said spring, a hydraulic pressurizing system including a motor, said motor having operably connected thereto a low pressure pump and a high pressure pump, a hydraulic fluid reservoir, a first hydraulic passageway connecting said reservoir to said low pressure, a second bydraulic passageway connecting said low pressure to said high pressure pump, a differential control valve, said differential control valve including a bore, a piston in said bore providing a vented and a low pressure chamber therein on opposite sides of said piston, a pair of spaced apart ports in said high pressure chamber, a third hydraulic passageway, one of said ports being a high pressure port and the other said port being connected to said reservoir by said third hydraulic passageway, a single port in said low pressure chamber, said piston having a portion of reduced area for sealably engaging said high pressure port and thereby blocking flow through said high pressure port in a first position of said piston and for allowing fluid flow therethrough in a remote position of said piston, a fourth hydraulic passageway connecting said second passageway to thelow pressure port of said differential control valve, a fifth hydraulic passageway connecting said high pressure pump to said hydraulic jack, a check valve in said fifth passageway adjacent said high pressure pump, a sixth hydraulic passageway connecting said fifth passageway remote from said check valve to said high pressure port of said differential control valve, means responsive to the discharged condition of said stored energy spring for energizing said motor to drive said low pressure pump and said high pressure pump, said low pressure pump providing fluid at low pressure to said high pressure pump and to the low pressure chamber of said differential control valve through said sec-0nd and fourth passageways respectively, said valve piston being moved thereby to the high pressure port blocking position, said high pres sure pump applying fluid at high pressure to said hydraulic jack and to the blocked high pressure port of the differential control valve through said fifth and sixth passageways respectively whereby said hydraulic jack is operated to charge the energy storage spring, the pressure differential developed in said piston preventing escape of high pressure fluid to the reservoir therethrough, means responsive to the latching of said spring in its fully charged position for de-energizing said motor, said low pressure fluid flowing back through said low pressure pump to said reservoir when said motor is de-energized thereby relieving the pressure in said dilferentia'l control valve thertofore holding said piston in said high pressure port blocking position so that the high pressure fluid in said hydraulic jack may then flow through the sixth passageway, the vented chamber of said differential control valve and said third passageway, serially, said third and sixth passageways and said vented chamber providing a low hydraulic resistance path for the hydraulic fluid in said jack to flow to said reservoir when said stored energy spring is released for closing said circuit breaker,

4. An energy storage mechanism according to claim 3 wherein flow restricting means are provided to control the rate of flow of fluid from said hydraulic jack when said stored energy spring is released from its fully charged position to provide control-led discharge of the energy stored therein.

5. An energy storage mechanism according to claim 4 wherein said flow restricting means includes a manually operable member to selectively control the rate of flow of said fluid continuously from full off to full on.

'7 8 6. An energy storage mechanism according to claim 4 wherein said control means is adjustable to control the wherein said differential control valve is provided with Tate of flow 0f fiuld from 881d J F RTOVldfi control means for maintaining said piston in said high contronfid release of the energy Stomd 111 531d pressure port blocking position to inhibit release of the energy stored in said spring.

7. An energy storage mechanism according to claim 6 EDGAR W. GEOGHEGAN, Primary Examiner.

No references cited.

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