US2960186A - Spring tensioning device for the actuation of circuit breakers - Google Patents

Description

Nov. 15, 1960 Filed Jan. 10, 1955 A. LATOUR SPRING TENSIONING DEVICE FOR THE ACTUATION OF CIRCUIT BREAKERS FIG. I.

4 Sheets-Sheet l INVENTOR l ANDRE LATOUR.

BY MM M ATTORNEY Nov. 15, 1960 A. LATOUR SPRING TENSIONING DEVICE FOR THE ACTUATION OF CIRCUIT BREAKERS 4 Sheets-Sheet 2 Filed Jan 10, 1955 m a 25%? M .b w m INVENTQR ANDRE LATOUR. BY

ATTORNEY NOV. 15, 1960 LATQUR 2,960,186

SPRING TENSIONING DEVICE FOR THE ACTUATION OF CIRCUIT BREAKERS Filed Jan. 10, 1955 4 Sheets-Sheet 3 FIG. 4.

INV ENTOR ANDRE LATOUR.

M 44mm ATTORNEY Nov. 15, 1960 LATQUR 2,960,186

SPRING TENSIONING DEVICE FOR THE ACTUATION OF CIRCUIT BREAKERS Filed Jan. 10, 1955 4 Sheets-Sheet 4 I39 141 I40 FIG. 5.

J l6l I48 -:-l66 1 M82 FIG 8 i l |9o- I89 INVENTOR I ANDRE LATOUR.

ATTORNEY Unite SPRING TENSIONING DEVICE FOR THE ACTUA- TIGN OF CRUUIT BREAKERS Andre Latonr, Grenoble, France, assignor to Etablissements Merlin & Gerin, Grenoble, France Filed Ian. 10, 1955, Ser. No. 480,951

Claims priority, application France Jan. 28, 1954 3 Claims. (Cl. 185-40) ment of an energy source of moderate capacity and of apparatus of moderate size, small space requirement and little cost of construction and attendance.

With this object in view, the invention provides for a device by means of which power of low magnitude is intermittently withdrawn from the source of energy, a device which makes it possible to tension the spring step by step and which is characterized by small space requirement, reduced cost and by the simplicity of the means employed as well as by the facility with which the energy withdrawn at each moment may be regulated.

In the device according to the invention, the spring is tensioned stepwise, in intermittent action at a predetermined pulsating flow rate of energy supply, under the action of a tensioning member operated by a pulse rcsponsive driving mechanism to which energy pulses controlled by a pulse controller are supplied pulsatingly.

In further development of the invention, these energy pulses are intermittently supplied to the spring tensioning member through a driving mechanism which includes a motor having a reciprocatory, movable member and motion transmitting mechanism which connects the movable member with the spring tensioning member. This motion transmitting mechanism will convert each cycle of the motor movement into a fraction of the total stroke of the spring tensioning member or a fraction of the spring expansion or compression whichever the case may be when the spring is tensioned. The supply of energy from its source to the pulse responsive driving mechanism is under the control of a pulse controller which may intermittently connect and disconnect the source of energy to the driving mechanism or may generate directly or indirectly energy pulses to be supplied to the driving mechanism or the motor thereof. Owing to this pulse controller, the pulsating flow rate of energy, by means of which the spring is to be tensioned, may readily be predetermined through proper choice of the characteristics of the pulses, viz. their amplitude, duration, the intervals between the pulses and other characteristics.

In the embodiments hereinafter exemplified, I make use, as the source of intermittent mechanical energy, of an electromagnet pulsatingly energized and operatively connected to the spring to be tensioned.

To this purpose, the electromagnet, by means of a spring tensioned rocking lever and intermediary pulse responsive apparatus, will operate the spring tensioning member and will thus tension the spring, step by step,

Sttes Patent in accordance with the repetition rate of the energy pulses. The intermediary apparatus may be of the type which includes a step measuring gear by means of which the spring tensioning member is operated and the spring tensioned in steps of constant, definite length, such as by a ratchet gear, toothed rack or ratchet wheel. The in termediary apparatus may also be of the type which does not produce or require actuating steps of a constant, definite length but may operate or advance the spring tensioning member in steps of indeterminate amplitude. To this purpose, an incompressible fluid transmission or hydraulic drive, or clutches of the unidirectional wedge-grip type, or any other pulse responsive apparatus may be employed.

The pulsating or rhythmic energizing of the electromagnet may be effected by any conventional or convenient device, in this specification referred to as pulse controller which may also be specific apparatus developed in accordance with the invention as will be set forth hereinafter, a device or apparatus by means of which pulses of mechanical or electrical energy may be derived from a source of permanent energy.

The pulse controller may thus be a relay, a clockwork, or a motor, periodically or pulsatingly closing and opening a switch in the energizing circuit of the electromagnet, or the pulse controller may be an electric pulse generator energizing the coil of the electromagnet by rhythmic pulses, or it may be any apparatus by means of which rhythmic pulses are produced for a pulsating, step by step operation of the spring tensioning member.

The pulse controller, in accordance with a development of the invention, may also include or comprise control or switching means for the closing and opening of the supply circuit to the eleetromagnet or other reciprocatory motor, control or switching means which are 0p- .erated or controlled by the reciprocatory motion of the electromagnet or other .motor or of any organ reciprocated or rocked thereby.

Further features and objects of my invention will became apparent as the now ensuing specific description of the invention proceeds in which the invention will be described with reference to the accompanying drawings which form part of this specification and which by way of example illusrate various embodiments of my invention.

These drawings, however, are to be understood explicative .of my invention but not limitative of its scope. Other embodiments incorporating the principle underlying my invention are feasible without departing from the spirit and ambit of my appended claims.

Inthe drawings:

Fig. 1 is a schematical elevational view, partly in sec- .tion, of a deviceof the invention in which the spring is from the electromagnet through the intermediary of a hydraulic transmission;

Fig. 4 is a schematical elevational view, partly in section, illustrating as an example the application .of the spring tensioning member to an oil circuit breaker for the closing of the same;

Fig. 5 is a schematicalelevational view of an embodiment in which the spring is tensioned, or mechanical energy accumulated, from the electromagnet through the intermediary of clutches for unidirectional wedge grip;

Fig. 6 is a plan view of the embodiment of Fig. 5

Fig. 7 is an elevational view partly in section, along line 7-7 of Fig. 6; and

Fig. 8 is a diagram illustrating schematically the application of the operating shaft of the embodiment of Figs. and 6 to the actuation of a circuit breaker.

In the embodiment of Fig. l, the spring to be tensioned by the device of the invention is designated by 11. 12 is the spring tensioning member, in the embodiment illustrated a bar, provided with a toothed rack 13 and guided by guide rollers 14, 15. The movable contact of a circuit breaker is connected to bar 12 as will be described in detail hereinafter with reference to Fig. 4.

21 generally designates the electromagnet with its coil 22, the ferromagnetic frame or housing 23 or flux return path, and the movable magnetic core or plunger 24. The

coil 22 of the electro-magnet 21 is energized from a network 28 under the control of a pulse controller generally designated by 30. This pulse controller may be of any of the types hereinabove referred to, and is indicated diagrammatically in Figs. 2 and 3 by the dash-line square 30, and in the embodiment of Fig. 1 by a contact wheel 31 driven by a conventional motor 32, in the instance illustrated by an electromotor. The fingers 33 of contact Wheel 31, when motor 32 is energized and running, close and open, intermittently and rhythmically, the contact 34 in the energizing circuit of the electromagnet.

Stationary set screws 35, 36 and co-operating abutments 37, 38, provided at the plunger, limit the drop of plunger 24 when the coil of the electromagnet is de-energized and thus determine the amplitude of the stroke of the electromagnet.

Plunger 24, by means of link 41, is coupled to a rocking lever 42 pivotal about pivot 43 and biased by spring 44 so as, when coil 22 is de-energized, to pull and return plunger 24 into the rest position shown in Figs. 1 to 3. Rocking lever 42 carries at its end, pivotal about pin 49, the driving pawl 45 which, in the embodiment of Fig. l, engages the teeth of rack 13. Spring 46 holds the pawl 45 resilently in engagement with these teeth.

A holding pawl 47, pivotal about pin 50 and held in engagement with the teeth of rack 13 by a spring 48, blocks the return of the spring tensioning bar 12 after each advance step caused through pawl 45 and guided by the guide rollers 14, 15.

A stop 52 provided at bar 12 opens, on the end of the stroke of the spring tensioning bar 12, when spring 11 is fully tensioned, the stroke limiting switch 53 and stops through the opening of line 54, 55 the energy supply to the pulse controller 30 and the electromagnet 21.

When the tensioned spring is to be released, the pawls 45 and 47 will be pivoted out of engagement with rack 13 by means of proper release mechanism as is, per se, well known in the art. This mechanism, since not forming part of the invention, is merely diagrammatically indicated by the lever system 62 operable by hand, knob 63, or by remote control 64.

Fig. 2 illustrates a modification of the embodiment of Fig. 1 in which the tensioning of the spring is elfected through the rotational motion of a ratchet wheel 65. At each energy pulse, supplied from the pulse controller 30 to the electromagnet, the plunger 24, through the intermediary of rocking lever 42 and the driving pawl 45, imparts to the ratchet wheel 65, as indicated by the arrow G, a counter-clockwise motion which rotates the wheel one tooth, the wheel being held by the holding pawl 47 against any return movement. A lever 66 secured to the wheel 65 imparts to rod 67 a movement, guided by the bearings 68, 69, in the sense of arrow H, a movement which by means of the flange ring 71 seated upon rod 67 tensions the spring 70 carried by rod 67.

Spring 70 may be released by any conventional release mechanism similar to that diagrammatically shown in Fig. 1, here merely indicated by arrows pointing to 62. By means of such mechanism, when spring 70 is to be released, pawls 45 and 47 will be pivoted by hand or by remote control and against the action of springs 46 and 48 out of engagement with the ratchet wheel 65.

Fig. 3 shows an embodiment of the invention in which the steps of the spring tensioning member are not necessarily constant and definite as in the foregoing examples. In this embodiment, the spring 72 is tensioned by the intermediary of a hydraulic mechanism, comprising the pump 75, the hydraulic jack and the reservoir 87 or other source of incompressible fluid, respectively connected by conduits 78, 86 and 88 controlled by non-return valves 79, 83 and 89. These non-return valves, since well known in the art, are not shown here in detail but are merely indicated schematically by balls.

With each energy pulse supplied to the electromagnet 21, the rocking lever 42 will impart to the piston rod 76 and the piston 77 of the hydraulic pump 75 a downward stroke which, while opening the non-return valve 79, will drive the incompressible fluid, preferably oil, contained within cylinder 75, through the conduit 78 into the space of the hydraulic jack 80.

Under the pressure of the liquid delivered into the space of the hydraulic jack 80, piston 81 will move downwards and thus will execute one step and will, by means of its rod 82, tension the spring 72.

At the end of each pulse, lever 42 and piston 77, under the action of spring 44, will return into their initial rest position. On the return movement of its piston 77, cylinder 75 is refilled with oil drawn from the reservoir 87 through conduit 88, the non-return valve 89 opening under the diminished pressure within the space 75. The cycle is repeated with each pulse, until, after a predetermined number of pulses, spring 72 is completely tensioned and the energizing circuit is opened, for instance by a stop 53 provided upon the piston rod 82 and a stroke limiting switch 53, as will be described hereinafter in detail.

The return of piston 81 after each advance under the tension of spring 72 is prevented by the non-return valves 79 and 83.

In order to release the spring 72, non-return valve 83 may be pushed back by hand, by a knob 84, or by remote control as indicated at 85. The liquid above piston 81 may now rapidly return through conduit 86 into the reservoir 87 While the released spring 72 will pull by means of rod 82 the piston 81 rapidly upwards into its original rest position.

The operation of the device will now be more specifically described with reference to Figs. 1 and 4, exemplifying the device as applied to the closing of an oil circuit breaker.

In Fig. 4, the oil circuit breaker is generally designated by 90, the terminals of a network by 91, 92. The contact bridge 93 carries the movable contacts 94, 95. The contact bridge is operated by the command rod 96 held under tension by spring 98 extended between the housing of the circuit breaker and a sleeve 97 with which rod 96 is secured to the contact bridge 93. The stationary contacts are 99, 100, respectively, of any conventional type. The contacts are provided with the conventional locking or holding means, schematically indicated at 101, 102, and with the conventional releasing means which however are not shown here in detail since they do not form any part of this invention and are well known in the art.

The spring tensioning bar 12 is provided at its end with a cross piece to which two catches 106, 107 are pivoted, at 108, 109, respectively. The catches are inwardly drawn, resiliently, by means of a spring 110, their inward motion being stopped by abutments 111, 112 at the piece 105.

A truncated cone 115 is provided at the free end of command rod 96 for subsequent engagement with the catches 106, 107.

As long as the spring 11 is released, the catches 106 and 107 are at a distance from and do not engage the truncated cone 115. In this released position of spring 11, the stroke limiting contact 53 is closed, as Fig. 1

illustrates, and the pulse controller is energized in the following circuit: Terminal 28line 54switch 53--line 55-line 56-motor 32line 57line 58terminal 28.

The pulse controller, if in the form of a periodic switch as exemplified in Fig. 1, will intermittently and pulsatingly close and open, over switch 34, the energizing circuit of coil 22 of the electromagnet, thus supplying the coil with current pulses in the following circuit: Terminal 28line 54-stroke limiting switch 53l-ine 55- line 59coil 22line 60switch 34-]ine 61-line 58 terminal 28.

On the other hand, when a pulse generator is employed as pulse controller, the pulse generator will intermittently and rhythmically supply directly these current pulses to coil 22 over lines 59, 60.

With each arriving current pulse the electromagnet is actuated, the plunger 24 is drawn into the coil and rocks lever 42 about pivot 43 against the action of spring 44. This movement advances, through the intermediary of the driving pawl 45, the toothed rack one tooth, or step, in the direction of the arrow F. A return movement of rack 13 is prevented by the holding pawl 47.

The length of the stroke of the plunger 24 may be adjusted by means of the abutments 37, 38, and the adjustment of the set screws 35, 36, so that the stroke of the plunger corresponds to the pitch of the toothed rack or of the ratchet wheel, the ratio of the length of the levers being taken into account.

With each energizing pulse supplied to the coil 22 of the electromagnet from or over the pulse controller 30, the toothed rack is advanced one tooth and the spring 11 is gradually tensioned. As the spring 11 is gradually tensioned, step by step, the catches 106, 107 approach and, towards the end of the movement of bar 12, engage the surface of the truncated cone 115 as shown in Fig. 4, until, at the end of the stroke of bar 12, the catches 106, 107 under the action of spring 110 engage the truncated cone underneath its base 116, and the circuit breaker is thus ready for being closed by means of the actuating spring 11.

As soon as the tensioning of the spring and also the coupling with the command rod 96 of the circuit breaker are completed, and the rack has reached the end of its stroke, the abutment or stop 52 opens the stroke limiting contact 53 and thus cuts ofli the energy supply to the electromagnet.

When the circuit breaker is to be closed, the spring 11 will be released by any conventional or convenient means, for instance by the lever mechanism schematically indicated in Fig. 1.

Through the operation of this lever mechanism, the driving pawl 45 and the holding pawl 47 will be pivoted, against the tension of their springs 46 and 48, and the pawls will be lifted out of engagement with rack 13. The release bar 12, under the action of spring 11, is displaced abruptly in a sense opposite to arrow F and is returned to its starting position. Through this movement, since the catches 106, 107 hold the command rod 96 of the circuit breaker engaged from underneath, the contact bridge is instantaneously moved upwards and the circuit breaker will be closed. Thereon, the contact bridge will be held blocked in the closed position by the conventional means. At the same time noses 116, 117 provided at the catches 106, 107 enter between and engage the stationary abutments 118, 119, respectively. The catches are thus spread from each other and release the cone 115 at the end of the closing stroke of contact bridge 93; cone 115 with the command rod 96 and contact bridge 93, however, being held in this upmost position by the conventional holding means of the contact bridge.

The circuit breaker may subsequently be opened by releasing the blocking means of contact bridge 93 as conventional in the art and thus not shown here.

With the return movement of bar 12, contact 53 closes 6 again, the pulse controller is again energized and-supplies energizing pulses to coil 22 of the electromagnet. However, the electromagnet and the rocking lever will work idly until the pawls 45 and 47 have been released for engagement with the rack. Spring 11 will then be tensioned again automatically. Bar 12 will be displaced and at the end of its movement will again engage the command rod of the circuit breaker. Should at the time when the pawls are released the circuit breaker still be closed, the catches 106, 107, released from the abutments 118, 119 at the beginning of the downward stroke of bar 12, will slidingly engage the rod 96 underneath the cone at a distance therebelow sufiicient to allow, subsequently, for an unimpeded opening stroke of the contact bridge of the circuit breaker.

In order to provide for sufficient time and allow the rack and the spring to return to their rest position, stroke limiting contact 53 will conveniently be a retarded closing contact.

The air-space above or the stroke of the electromagnet plunger 24 will correspond, as already pointed out hereinabove, to the pitch of the teeth of rack 13. On the other hand, the air-space is determinative of the power withdrawn from the network for energizing the electromagnet. The device of the invention may be adapted by extremely simple means to the capacity of the energy source or to the magnitude of the power which it is intended to withdraw from this source. To this purpose, the part 13 which carries the teeth of the rack may be made exchangeable.

In case it is desired to withdraw only a very small amount of energy with each impulse, it will suffice to provide upon the bar 12 a rack with teeth of a small pitch and adjust the stroke of the plunger of the electromagnet correspondingly by adjusting the set screws. However, with a source of sufficient power from which energy of great magnitude may be withdrawn at once without inconvenience and if it is desired to reduce the length of time needed for the tensioning of the spring, a rack of great pitch of the teeth will be secured to the bar 12. The air-space and correspondingly the stroke of the plunger 24 will then be proportionally increased by adjustment of the set screws 35, 36.

The velocity with which the spring will be tensioned may also be varied by regulating the frequency of the pulses produced in the pulse controller 30, under the condition, of course, that the type of pulse controller employed allows of such regulation.

It will readily be understood that the device as. illustrated in Figs. 2 and 3 may similarly be connected at or by means of the rods 67, 81 to the movable equipments of circuit breakers for actuating them by means of springs 70 and 72 and that the devices may actuate the circuit breakers by means of expansion springs, Figs. 1 and 3, as well as by compression springs, Fig. 2.

Figs. 5 to 8 illustrate a further embodiment of the invention where the necessity of imposing upon the electromagnet 'a definite stroke is advantageously avoided.

In this embodiment, the electromagnet 21 with its plunger 24- is operatively connected through a unidirectional wedge-grip clutch to a shaft 131 carried in bearings 132, 133. A second unidirectional wedge-grip clutch is provided between shaft 131 and a stationary point of the framework. Each clutch includes a Wheel rim or ring 134, 137, respectively, carried freely revolvable upon a hub 135, 138 secured to the shaft 131. Each of the clutches further comprise a cam disc 139, 143, respectively, secured to the hubs 135, 136, the cam discs being provided with cam rises 140, 144. Cam rollers or balls 141, 145, or other elements with releasable wedge action, are urged by springs 142, 146 between the cam rises 140, 144 and the inner circumferences of the rings 134, 137.

Figs. 5 and 7 show that disc 139 and ring 134 grip each other through wedging of the cam rollers when ring 134is rotated clockwise relatively to cam disc 139 or when the cam disc is rotated counter-clockwise relatively to ring 134 and, conversely, that the grip between both is released when ring 134 is rotated couter-clockwise relatively to the cam disc 139 or when the cam disc 139 is rotated clockwise relatively to ring 134. Ring 137 and cam disc 143 are operative in the same sense.

Ring 134 carries a rocking lever 148 which by means of link 41 is connected to the movable core or plunger 24 of the electromagnet. With each. power stroke of plunger 24, ring 134 will grip cam disc 139 and, by means of hub 135 will thus advance the shaft one step, the amplitude of which is indeterminate and will readily adapt itself to the prevailing conditions of the mechanism.

A spring 149 extended between the rocking lever 148 and the framework of the apparatus will effect the return stroke of plunger 24. With this return stroke, ring 134 will be rotated counter-clockwise and will release the grip on cam disc 139 and thus on shaft 131. Any return movement of shaft 131 is prevented through the second clutch device. Ring 137 of this device is held from rotation by a lever 150 of one piece with it and secured at its free end to a bracket 151. The clutch of this device, Fig. 7, will release its carn disc 1 53 and thus shaft 131 with each advance movement, clockwise, of the shaft, will however wedge the cam rollers 145 between the cam rises 144 and the inner circumference of ring 137 and will thus block shaft 131 when this shaft tends to return, counter-clockwise.

Shaft 131 is operatively connected, by means of intermediary mechanism with the head 155 of the spring tensioning member, push rod 154, of the spring 152 which is to be tensioned and is thus to be charged as an energy accumulator with mechanical energy through the periodic drive of the electromagnet, as will be described in detail hereinafter.

periodicity or rhythm conformable to the device selected. This pulse controller may be of any one of the types hereinabove described with reference to the preceding figures or may be of the specific type illustrated in Fig. 5 which will now be described.

In this embodiment, the motion of the driving mechanism itself is employed for periodically supplying and cutting off the energy to the driving mechanism.

The electric energy is supplied to the coil 22 of the electromagnet from an electric network 160. The intermittent command apparatus is generally designated by 161. In the example illustrated, a contact 172 is provided upon the shaft 131 rotating therewith. Contact 172 is connected through line 162 with one terminal of the network 161) and may slide upon a ring-shaped contact rail 173 and finally reach, in the tensioned position of the spring, a contact 176 separated from rail 173 through an air gap 163. Rail 173 is connected at its one terminal A through line 164 to the one terminal of coil 22, the other terminal of the coil leading over the command apparatus 161 and line 165 to the other terminal of the network 160.

The command apparatus 161 includes a tumbler switch 177 pivotal about pin 181 and about the axis of a pin 182 tiltable with it and through a slot of which it may slide. Arm 183 of the tumbler switch carries the contact 179 opposite a stationary contact 178 for cooperation therewith. The tumbler contact is operated by a finger 180 secured to the rocking lever 148 so that at the end of each downward or power stroke of the plunger 24, the tumbler contact is tilted counter-clockwise about pin 181 and thus opens the contacts 178, 179

magnet coil 22.

Spring 149 now draws back the rocking lever 148 and plunger 24 returns to its upward position. At the end of this return or upward stroke of the plunger, finger 188 will now push and pivot the tumbler switch clock- 'WlSe about pin 181 and will thus close the contacts 178, 179, so that again an energizing pulse will be supplied to the coil of the electromagnet. This cycle is rhythmically repeated.

In order to ensure a precise and complete opening and closing motion of the tumbler switch, the lever of this switch is in form of a toggle lever, comprising the toggle arms 183, 184 articulated at 185. Toggle arm 184 is slidable within the swivel pin 182, and the toggle sys tem is urged into the broken positions by means of a spring 186, carried upon arm 184 and tensioned between swivel pin 182 and the head of arm 184 at the joint 185.

The device operates as follows:

The device as shown in Fig. 5 is in the position where the spring 152, which is to actuate the mobile equipment of a circuit breaker, is tensioned and the device thus is ready to close the circuit breaker. This may be effected, for instance, by means of shaft 131 which may be coupled to the command shaft 191 of a circuit breaker by any conventional or convenient means. These means, since they do not form part of the invention, are not described here in detail but are merely diagrammatically indicated in Fig. 8. Shaft 131 is shown as provided with a cam finger 187 which when shaft 131 is turned clockwise will strike against a earn 188 on the command shaft 191 of the movable lever 189 of a circuit breaker 190 and will thus pivot the lever into the closed position.

In the position of Fig. 5, the crank arm and the link 156 are in the dead point or stretched position of the toggle joint they form, thus both members are in the direction of the axis O-X, the extension of the axis of spring 152. Contact 172 is upon contact 176, as illustrated, and the current is interrupted. The command 161 is at rest.

In order to close the circuit breaker, a push button contact 175, connecting contact 176 to line 164, is closed. The energizing circuit of magnet coil 22 is thus closed in the following circuit: Network line 162contact 172-contact 176push button contact 175line 164- coil 22contacts 178, 179-line -network160.

The plunger 24 of the electromagnet is pulled downwards and, by means of link 41 and rocking lever 148, rocks ring 134 and advances it one step, clockwise. 'Clutch 139 grips hub 135 and turns shaft 131, thus moving thecrank am 155 out of the dead point position. Spring 152 is abruptly released, unimpeded by the clutches 139, 143 anddrives the crank arm clockwise and with it the shaft 131 one step. Shaft 131, by means. of the cam mechanism 187, 188 or by any other convenient or conventional means will actuate the command shaft 191 and close the circuit breaker 189, 190.

Let us assume, the deflection of the crank arm when the spring is released corresponds to an angle 0:, inside of which the deflection of the circuit breaker arm for closing the circuit breaker lies. As soon as the crank arm 155 I contact 172 will also have been deflected about this angle and will have reached the nearly circular contact rail 173. The circuit of the pulse controller is now closed through line 162contact 172-contact rail 173 and the supply of energy pulses to the magnet coil is started. With each pulse, ring 134 is an angular distance corresponding to the stroke of the plunger of the electromagnet, and cam disc 139 will be advanced one step, gripped by the cam rollers 141 now wedged between the cam rises 140 and ring 134. With the advance of cam disc 139, shaft 131 will also be advanced.

This pulsating advance is continued until the crank arm 155 has described an angle of 360a and has returned to the dead point position O-X. Before this point is reached, during the course corresponding to the angle [3, the spring 152 is re-tensioned. With the last pulse exerted by the electromagnet and before the crank arm reaches the dead point, contact 172 leaves the contact 173 at the point A and comes to rest upon the contact 176'.

The circuit of the pulse controller thus is opened, the electromagnet stops operating and the crank arm remains in the position O-X.

Since, after the last pulse, plunger 24, drawn upwards by spring 149 and rocking lever 148, closes the contacts 178, 179, the command apparatus is again ready for the next closing operation of the circuit breaker, which, as has just been described, is effected by pressing the pushbut'ton contact 175.

During the tensioning phase of operation and the return or upward stroke of the plunger, the stationary ring 137 and its clutch 143, 144, 145 will, as described hereinabove, prevent crank arm 155 with shaft 131 from turning, under the bias of spring 149, counter-clockwise.

Should the network 78 which energizes the coil of the electromagnet be a direct current network, contacts 178, 179 may be shunted by a capacitance 166, and the coil 22 by a resistor 167.

Obviously numerous variations and modifications of the instant invention are possible in the light of the above teachings. Accordingly it is to be understood that with-in the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.

I claim:

1. In combination with a circuit breaker of the type closed by a strong spring to assure quick closing, a spring tensioning member connected to said spring, an electromagnet, motion transmitting mechanism for operating said spring tensioning member in response to the vertical reciprocating movement of the core of said electromagnet, a source of electrical energy, supply lines electrically connecting said electromagnet to said source of electric energy, a pulse controller interposed in said supply lines and responsive to the vertical movement of said core for controlling the flow of energy from said source to said electromagnet in pulses at a predetermined rate thereby to actuate said motion transmitting mechanism, operate said spring tensioning member and tension said spring at said predetermined rate of flow of the driving energy supplied to said spring actuating member, said motion transmitting mechanism including a spring tensioned rocking lever linked to said movable core, a unidirectionally operative coupling gear for wedge-grip operatively connecting said rocking lever to said spring tensioning member, said coupling gear including a shaft operatively connected to said spring tensioning member, said unidirectionally operative coupling gear comprising a pair of clutches, each clutch including a cam disc mounted upon said shaft and having cam rises and cam rollers for cooperation therewith, a ring being disposed peripherally about each cam disc, coaxially therewith and with the shaft, one of said rings being rigidly joined to said rocking lever to be rockable therewith, the other ring being stationary; said cam rollers being disposed between said cam rises and the inner circumferences of said n'ngs, thereby to wedge by the one clutch said rockable ring to the cam disc appertaining thereto and to couple said rockable ring to said shaft upon a power stroke of the movable member and to advance the shaft, the grip of the other clutch upon the stationary ring being released during this advance motion of the shaft, whilst, during the return stroke of the movable member, the ring of the rocking lever is released by its clutch, the shaft, however, being prevented from any return movement, under the tension of the spring, through the other clutch Wedging its cam disc to the stationary ring.

2. A device as set forth in claim 1 including a crank arm mounted upon said shaft, a connecting rod connecting said crank arm to said spring tensioning member, said crank arm and said connecting rod constituting a toggle joint disposed with relation to said spring tensioning member so as to allow full revolution of the shaft with passage through the stretched position of the joint, the spring suddenly being released under its tension in a first part of the revolution through collapse of the joint in the sense and towards the side of the advance motion of the shaft, the spring being tensioned through continued rotation of the shaft in the same sense until, on further movement in the same sense, the joint approaches from the other side its stretched position; detensioning of the spring and collapsing of the joint during this phase of operation being prevented through the cooperation of the clutches.

3. A spring tensioning device, particularly for the actuation of circuit breakers, including a spring, a tensioning member connected to said spring, an electromagnet, motion transmitting mechanism including a spring tensioned rocking lever linked to the movable core of the electromagnet, and intermediary mechanism operatively connecting said rocking lever to said spring tensioning member; supply lines electrically connecting said elec tronmgnet to a source of electric energy, a pulse controller associated with said supply lines, said pulse controller including switching means operatively connected to said rocking lever and connected to said supply lines, thereby on rocking motion of the rocking lever, alternatingly to connect and disconnect said electromagnet to and from the source of energy and thus to operate said spring tensioning member and tension the spring at a predetermined pulsating flow rate of the driving energy supplied to the spring tensioning member.

References Cited in the file of this patent UNITED STATES PATENTS Re. 22,853 Crabbs Mar. 18, 1947 10,128 Clark Oct. 18, 1853 2,470,675 Allan May 17, 1949 2,646,660 Schild July 28, 1953 2,674,345 Favre Apr. 6, 1954

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