IL32008A - Low-voltage electric circuit-breaker - Google Patents

Description

LQW-VOIEAGB ELffCTRIC CIRCUIT- BREAKER Tim nner? Oman PIT ^OBQ The present invention relates to a low-voltage electric circuit-breaker which may be of the single-pole or multi-pole type and the function of which is primarily to provide automatic protection for one or more electric circuits against current overloads exceeding a predetermined nominal value.

The invention relates more particularly to a circuit, breaker which can be moved manually into the make or break position and which may be considered also as a current cutout.

Devices of this kind normally include a sensing element responsive to the electrical overload, that operates on a latch mechanism which trips open the electrical contacts in the event of a fault, thus breaking the electric circuit in question.

Also known are devices in which a tripQout responsive to an overload is prevented if a durable force is applied to a manual "make" element, such a circuit-breaker being known as an "interdicted trip-out" type circuits-breaker, whereas in\ other devices trip-out is unrestrained despite the application of such a force. , It is one object of the present invention to provide \ both these features without notable modification.

It is another object of the invent on to make a \ circuit-breaker inpervious to the effect\ of mechanical stresses V particularly vibration, irrespective of their direction. ί It is still another object of the invention to pro-vide simple arc blow-out means in such a circuit-breaker.

The present invention accordingly relates^ to a circuit-breaker including a fiKed contact, a movable latch in the form of a cylindrical member surrounding the balls and the operating rod and totatable about the axis of the operating rod, the latch being biased by resilient means into a restraining position in which surfaces of the latch restrain the balls in co-operation with the shoulder on the rod in the operative position of the rod to maintain the contacts closed, the latch being rotatable against the ti of the biasin means b drive m ans actua d b c . .

Perferably, the balls are associated with a fixed ;/ guide cage interposed between the rod and the latch. 'i In one specific form of embodiment, rotation of the i latch and movement of the rod to its operative position can be produced by coaxial manually operated members, one of which is a make button and the other a break bush surrounding the button, the bush having a salient external portion enabling a pulling force to be exerted thereon and being associated with means for converting such pulling motion into rotation of the latch.

The description which follows with reference to the accompanying non-limitative exomplary drawings will give a clear understanding of hovr the invention can be carried into practice.

In the drawings: Figures 1 dtfirough 8 are perspective showings of various forms of embodiment of a circuit-breaker according to the ^rese t invention, notably in respect of the securing method and the connecting method.

Figure 9 is a longitudinal sectional view of such a circuit-breaker in its tripped or break position.

Figure 10 is a sectional view of the circuit-breaker in its make position.

Figure 11 is a sectional view through the line XI-XI of Figure 9.

Figure 12 is a sectional view through the line XII- j Figure 13 is a sectional iew through the line ; ¾1- II of Figure 1Q.

Figures 14 through 17 show alternately, in section an¾ in perspective the mutual positions of the actuating rod ■·' i the ^alls, the ball cage and the balanced rotary latch, in ) the make position and in the break position respectively.

/ Figure 18 is a detail vievr in perspective of the manual control of the balanced rotary latch.

Figure 19 portrays diagram atically and in persp tive the magnetic effect of the field developed by the overloa sensing thermal switch at the location where the breaking arc develops, whereby to blow out the same.

In its forms of embodiment shown in the accompanying drawings, the circuit-breaker includes a lohgish cylindrical body Ί from. which projects a central make-button 2 surrounded by a bush J formed with a flange that constitutes a break member likewise protruding from the body. Figure 1 shows the break position in which button 2 protrudes considerably, while Figure 2 shows the make position in which button 2 remains depressed and projects only very slightly above flange 4.

As shown in Figure 3, the body 1 is formed at the button end with a threaded reduced portion 5 projecting above a shoulder, whereby to enable the body to be secured in a panel hole by means of a nut , The body 1 may alternatively be formed with a further reduced portion 8 at its base to allow it to be fixed in a projecting position to the bottom of a housing, for example.

Other alternative securing methods are possible, notably by providing a base-plate 9 beneath the body 1 in order to enable the latter to be secured by screws 10 to a distributor rail 11 formed to that end with tapped holes 12 and with an intermediate hole 15 for passage there-through of · the insulating sheath 14 of a conductor terminating in a bush , which engages over a central pin 15, which pin forms one of the poles and the base-plate 9 the other.

Figure β shows another embodiment which comprises ; brackets 16 on to which connecting taps 18 are secured by screws 17 and associated washers.

In Figure 7 the connections are made by means of soldering terminals 19·.

Lastly, Figure 8 shows a junction method utilizing a coaxial connector 20 provided with a knurled thumbscrew 21 adapted to cooperate with a bush and pin unit 22 at the base of body 1, the thumbscrew cooperating with the threaded portion 8a of said base.

In all cases the electrical connections and the insulations between poles and conductors external to the circuit-breaker are provided by any convenient means.

The embodiments shown- in Figures 9 through lj'> are s: milar in configuration to that of Figure 5* and these figures depict the internal mechanism of the device. The circuit-breaker portrayed in the figures is of the free-tripping type i.e. in which opening of the contact in the event of an overload is possible and effective even if the button 2 is kept depressed manually.

The button 2 can be made rigid with a central rod 2> through the cooperation, inside a blind hole formed in button 2, of a head-fitting 2k formed with a diametrical passa ge therethrough into which are inserted two balls 25 with a spring 26 therebetween. These balls are urged by spring 2o into a groove 27 formed within button 2, with the upper face of the groove bearing against said balls, over a substantially diametrical plane thereof.

The other end of rod 2J> is formed with a housing for a contact-pressure spring 28 which reacts against the head of an insulating rod 9 slidably mounted in the housing of spring 28 and restrained therein by a keeper ring 30. The projecting end of rod 29 carries a travelling contact Jl, and this compound forms the travelling pin of the circuit-breaker.

Button 2 is formed with a skirt ^2 the bottom of which is formed with a catch portion 33· Skirt 32 is engaged into a guideway on to the end of which is screwed bush 3 with flange 4. At the point where guideway J> joins on.- to a reinforcement 35 which terminates it are recesse's 36a which permit projection into said guideway and retention in position of an' elastic ring J>6 for temporarily restraining the catch portion 33 of button skirt 2, which portion, in its opposite .. . - f position, is positively arrested against a shoulder 37 formed on the guideway. ' v A spring 8 is interposed between a shoulder 39 for-med within button 2, beneath groove 2 , and a shoulder 40 formed on a cage 41 to be described hereinafter. Spring 38 surrounds a break sleeve 42 the upper edge of which is formed with a bevel 43 capable of reaching the balls 25 by passing between the skirt 3 (with its base on .the hollow portion of button 2, beneath the rectangular groove 27) and the edge of head 24.

Another spring 44 is interposed between head 24 and shoulder 40, but its reaction surface is within sleeve 42.

A third spring 4 is interposed between terminal shoulder 46 of threaded portion 5 of body 1 and the shoulder adjacent recesses 6, between guiding sleeve 3½ and reinforcement 35 · Through the medium of matching splines 57a , reinforcement 35 cooperates with the said cage 41 of latching balls 48 assembled in diametrical pairs in associated housings 4 .

'At its top, cage 4l is bounded by a frusto-conical shoulder 50 formed with a passageway therethrough for rod 24 and against which bears a matching frusto-conical shoulder 51 which bounds the rod 2 and the reinforcement 2 forming the^^. housing of spring 28, which reinforcement passes freely throurh cage 41. .

Cage 41 comprises a threaded base 53 having an abutment rim, and this base is screwed into a suitably tapped reinforced portion ^ of the inside wall of body 1.

Cage 41 is surrounded by the reinforcement 35 and the latter is in turn surrounded by a cylindrical latch 55 the end section of which rests upon the bottom of base 53» Externally, the other end of the latch 55 is formed with a head >6 opposite a corresponding shoulder on body 1.

Latch 55 a d reinforcement ¾ of guiding sleeve 3 cooperate through the medium of associated helicoid ramps 57 (see also Fig. 18).

A return torsion spring 58 is interposed between the bottom 53 (to which the spring is fastened) and the head 56 (to which the spring is also fastened) whereby to tend to rotate latch 55 back into a latching position to be referred to hereinafter.

Internally latch 55 is formed on its cylindrical surface 59 with cylinder-sector shaped recesses βθ adapted to receive the balls 48 and thereby permit full disengagement of shoulder 51 on reinforcement 52.

Inside body 1, beneath the base 53.» is an insulating sleeve 6l formed with a groove 62 into which the edge of body · 1 is set without extending beyond the bottom of the groove.

The bottom of sleeve 6l has set thereinto a threaded bush 63 on to which is secured the conducting base-plate 9 wit interposed washers and suitable leak-proofing between the various screwed parts. Internally, bush 63 receives a cup 64 at the bottom of which is a fixed contact 65 electrically connected^ to an axial connecting pin 66, said cup being made of insulating material.

A bi-metallic strip ' 67 rolled into a cylindrical coil is wound around the periphery of cup 64 and has one end electrically connected to bush 65 which is in turn connected to base 9, the 'free other end of bi-metallic strip 67 being electrically connected through a conductive flexible braid 68 to travelling contact j51.

This free end of the' bi-metallic strip forms a hook 69 capable of cooperating with a tang 70 made of insulating material and set into a corresponding recess in latch 55, and this tang penetrates into the end section of the latch and passes through a notch in the bottom 5* the edges of said notch forming stops for the two directions of motion of latch 55. ' 1 ' < A groove and tongue arrangement 71 prevents rotation between insulating sheath 6l and the base 23 which is securely ' screwed into body 1.

The electric circuit which is established passes through the pin 66 and the fixed contact 65 on the one hand, then through the travelling contact stud 31, the braid 68, the ; bi-metallic strip 67, the bush 63 and the base 9, on the other .

The theory of operation of a circuit-breaker as hereinbefore described is as follows : Starting with the open position of the contact shown in Figure 9> if button 2 is then depressed, retention of the balls 2 in groove 27 causes rod 25 to- be moved. The locking balls 8 are lodged partly in the notches 60. Inward movement of button 2 is continued until stud 31 meets fixed contact 65, the contact pressure being provided by the compression of f spring 28.

In this con iguration the locking balls 48 are free to move towards-'rod 25 by moving on to frusto-conical shoulder 51, and in this position the balanced rotary latch 55 can rota-te responsively to spring 8 and move from the position shown in Figure 1Γ« to that shown in Figure 12. As shown in Figure 10. the balls 48 are kept proximate the rod 23 and prevent it from retracting, being then retained on the cylindrical inner surface of latch 55 · As button 2 is depressed further still, the catch passes beneath the ring 36, which then holds button 2 in its depressed position (being required to overcome the compression of spring 38 only).

Prior to completion of the inward travel of button 2 , balls 2 will have cooperated with the bevel 4 on the break sleeve 42 and will thus have left the groove 2 and be held closely together, with attendant compression of spring 26, within the internal bore of button 2. This disengages rod 2 from button 2, causing it to rise and to be arrested solely by the balls 48 resting against shoulder 51.

Should an electrical overload occur, bi-metallic strip 67 will undergo expansion by the Joule effect, causing its terminal hook 69 to meet the tang 70 and to make the latte.r rotate balanced rotary latch 55 against its countering spring 58. When this rotation causes the notches βθ to register with the passages 49, the slight conicity of shoulder 51 drives the balls 48 into notches βθ, thereby freeing the rod and causing'' it to move outwards once more through relaxation of spring 28 in conjunction with relaxation of spring 44. When the head 24 contacts the bottom of the bore in button 2, the catch 33 beneath ring 36.gives way and, responsively to spring 38, button 2 emerges once more from. bush 3 until it is positively arrested when the catch 33 abuts against shoulder 37', as shown in Figure 9 whereupon the balls 25 cooperate once more" with the groove 27 through the frusto-conical shoulder 51 meeting the corresponding shoulder 50 on cage 41.

Manifestly, any pressure tending to maintain button 2 depressed will not prevent the circuit from being opened by reason of the freedom of travel now possessed by the head 24 in button 2, balls 25 being then clear of groove 27 and encountering no obstruction.

Protrusion of button 2 furthermore Indicates opening of the contacts.

Preparation for a fresh trip-in manoeuvre requires relieving the pressure on button 2 and a retraction of the latter in order to re-set the balls 25 in groove 27.

In this situation the action of spring 44 is added to that of spring 38 so as to cause the catch 33 to disengage from ring 36.

The latching effects areAllustrated separately and > more ''schematically, in perspective and in sectional view respectively, on Figures 14 through 17- Starting from the make position shown in Figure 10, if it is desired to deliberately open the circuit all that is necessary is to pull back bush 3 by gripping flange 4. This action oompresses spring 45 and causes head 35 to be guided by facing straight splines 57 formed in the head 41 of break sleeve 42 and in the rein orcement 35 o guiding sleeve 34, thereby producing a rotation of- latch 55 through the agency of helicoid ramps 57. At the same time the 'balls 48 are released as a result of penetrating into the notches 60 in said latc ^^ when the latter has rotated sufficiently, and the effect on the rod is then identical to that hereinabove described in respect of trip-out , obtained with the bi-metallic strip.

Figure 18 shows diagrammatically how the trip-out bush or button 5 cooperates with latch 55· It should be noted that the conjugate helicoid ramp:; 57 have sufficient clearance therebetween to permit rotation of the latch in response to the bi-metallic strip when button 5 is inoperative. Contact against one of the sides of these ramps is obtained by the action of spring 8, which takes up l.; play in the operation of button 2, since the operative sides of ramps 57 are used when a pull is exerted on button J>, so that response to such a pull is immediate.

It should likewise be noted that bi-metallic strip 6 is disposed after the fashion of a solenoid developing an axial field under the effect of the current flowing through it;, and this field remains when the travelling and fixed contacts ; 31 and 65 separate, so long as the breaking arc subsists. The effect of this field on the conductive ionized channels formed by the arc causes the same to distend radially, resulting in powerful and instant blowing out of the arc. The arrows in : Figure 1 depict these effects.

It will readily be appreciated that the above arrangements permit compact and lightweight construction offe- ' ring great flexibility of utilization for a single type of · core design, that the contacts can be placed in a sealed chamber in .a gazeous atmosphere if need be, and that the latching mechanism is impervious to mechanical effects, notably vibration, for since the latch 55 is balanced it is unaffected by transverse vibration, and longitudinal vibra^ tion has no effect on it either. Being captive when latched, the balls 48 cannot be affected by longitudinal vibration, the more so since the angle subtended by the rusto-conical shoulder 51 can be very shallow, this angle being set, as a function -of the desired response sensitivity in opening of the contacts upon release, to determine the magnitude of the r*adial forces on the balls 48 when this occurs. in the case of torsional vibration, moreover, the fact that latch 55 is balanced, together with the diametrical arrangement of the balls, cause this to remain without effect.

The device hereinbefore described is a free-tripping circuit-breaker. Using the same component parts, however, it is possible to device an interdicted trip-out type circuit-breaker by eliminating the direct tie between rod 23 and button 2,notably by eliminating the ring j6, either of springs 38 or 44, the head 24 and its balls 2 , and possibly also the sleeve 42, provided that the springs have no tendency to warp..

Further, whereas the arrangements hereinbefore described relate to a single-pole circuit-breaker, the same components can clearly be used for a multi-pole circuit-breaker dependent on a single operating and latching system for all the poles, with each pole nevertheless remaining dependent on its own individual sensor, said sensors cooperating to act upon a single balanced latch so that a fault on any of the circuit:; should dependably result in all the circuits being opened.

It is furthermore manifest that changes could be made to the specific forms of, embodiment described hereinabove, notably in respect of the trip-out triggering sensor, it beir; possible for such sensors to be responsive to factors other than the intensity of the current flowing, or to have a response mode other than heating by the Joule effect (for instanc by generating a magnetic effect), the only requirement being that the sensors be capable of causing a rotation of the balanced -rotary latch in order to cause trip-out. In addition, the longish cylindrical body of the breaker may have any other convenient' shape, or several pairs of latching balls could be used, or the major part of the components could be obtained otherwise than by turning operations.

With regard to the bi-metallic strip, the latter may be compensated or not and may utilize direct heating, as stated above, or indirect heating if necessary.

The blow-out field could furthermore be channelled by an appropriate magnetic circuit.

In order to facilitate adjustments, rotationwise clamping means may be provided between the bi-rr.etallic strip and its attachment point. - The lealctightness of the contacts' envelope can be reinforced in respect. of atmospheric or celestial space factors by means of at least one deformable wall such as bellows (depicted schematically at 31a in Figure 9 ) , which may be of the metallic variety with the necessary insulation being provided at the joints by means of glass or ceramic bonds.

Claims (8)

Ρ,Α. 32008/11 WHAT IS CLAIMED ISt

1. A circuit-breaker including a fixed contact, a movable contact operated by an operating rod which is axially movable to an operative position in which the contacts are maintained closed against the action of return means urging the rod towards an inoperative position in which the contacts are open, at least one pair of balls located on opposite sides of the rod and co-operable with a sloping shoulder on the rod in the operative position of the rod, and a rotary latch in the form of a cylindrical member surrounding the balls and the operating rod and rotatable about the axis of the operating rod, the latch being biased by resilient means into a restraining position in which surfaces of the latch restrain the balls in co-operation with the shoulder on the rod in the operative position of the rod to maintain the contacts closed, the latch being rotatable against the action of the biasing means by drive means actuated by a^ sensing element into a release position in which notches in the latch, for receiving the balls so that they can move clear of the shoulder, are aligned with the balls whereby to release the rod and open the contacts.

2. A circuit-breaker according to Claim 1*· wherein the balls are associated with a fixed guide cage interposed between the rod and the latch.

3. A circuit-breaker according to Claim 1 or 2, wherein rotation of the latch and movement of the rod to its -10- P.A. 32008/11 operative position can be produced by coaxial manually operated members, one of which is a make button and the other a break bush surrounding the button, the bush having a salient external portion enabling a pulling force to be exerted thereon and being associated with means for converting such pulling motion into rotation of the latch.

4. A circuit-breaker according to Claim 3 wherein the make button is rigid with the operating rod for the movable contact,

5. · A circuit-breaker according to Claim 3 wherein the make button is associated with the operating rod for the movable contact through the agency of latching means whihh, when said button is thrust fully home, cooperate with means for releasing said latching means.

6. · A circuit-breaker according to any one of Claims 1 to 5» wherein the sensing element responds to an electrical overload, and also develops a directed magnetic field aaed to blow out the arc produced on separation of the contacts.

7. · A circuit-breaker according to Claim 6, wherein the sensing element is a bi-metallic helix heated by the electric current flowing through the contacts and forming a solenoid surrounding the path of the movable contact*

8. A circuit-breaker according to any one of Claims 1 to 7t including a chamber for the contacts which is formed with a flexible wall that seals off the chamber from the exterior* P.A. 32008/11 9· A circuit-breaker as hereinbefore described with reference to and as illustrated in the accompanying drawings* COHEN ZEDEK & SPISBACH