US2467653A - Electric cutout - Google Patents

Description

Apri i9, 1949. E. A. BERTHIER ELECTRIC CUTOUT Filed Feb. 18, 1948 5 Sheets-Sheet Apri 19, iSv-29u E. A. EERTHIE'R 2,467,653

ELECTRIC CUTOUT Filed Feb. 1.8, 11948 3 Sheets-Sheet 2 April 19, i949. E'. A. BERTHIER 24679653 ELECTRIC CUTOUT Filed Feb. 18,. 194s 3 sheets-sheet 3 R5 @5155/53 I l l Patented pr. 19, 1949 UNITED STATES PATENT OFFICE ELECTRIC CUTOUT Emile Andr Berthier, Villefranche-sur-Saone, France Secton 1, Public Law 690, August 8, 1946 Patent expires February 16, 1964 8 Claims.

The subject of the present invention is an electric cut-out designed to break an electric circuit when the value of the current exceeds a deter mined nominal value. A small excess of current causes it to operate. A dead short-circuit even repeated several times and involving considerable overloads Causes its operation without harm to its parts.

This cut-out is adapted more particularly for the protection of small power motors, domestic power and lighting installations, electric equipment or' vehicles, and in general `any electric circuits where a small excess current as well as a short-circuit may involve damage or accident.

In the cut-out according to the invention, a moving con-tact is carried by a flexible blade held in the set, circuit mak-ing position by engagement with a latch blade rockable on a -push rod and acted upon by a spring which lholds it engaged with the flexible blade, the push rod being itself held in its corresponding inward position by a pawl under spring action, operation of the cutout being caused by deflection of a bimetallic stri-p in series with the controlled circuit, which presses the latch blade into a housing in the lpush rod, so releasing the flexible blade which, being suddenly retracted, opens the circuit and strikes the tail end of the -pawl thereby releasing the push rod which a spring pushes into its outer, released position, the rocking blade at the same time reengaging the flexible blade. This re-engagement enables :the cut-out to be reset by depressing the push rod which is re-engaged by the pawl, while the flexible blade is returned `to contact making position.

A release button can be Iprovided which acts upon ya lever to rock it, the lever either acting on the tail end of the pawl or pushing the rocking blade into its housing.

The accompanying diagrammatic drawings show by way of example, some embodiments of the invention.

Figures 1 and 2 are vertical sections of :the cutout in set position, taken respectively on the line I-I of Figure 2 and 2-2 of Figure 1.

Figure 3 is a vertical section on the line I-I of Figure 2, but with the cut-out after operation, i. e. with the circuit opened.

Figures 4 and 5 are detail vertical sections of a modification of the contacts, shown respectively open, on the line 'l--fI of Figure 5 and closed, on the line 5--5 of Figure 4.

Figures 6 and 7 are similar views of another modification of the contacts shown respectively 2 open, on Ithe line `(i--E of Figure 7, and closed, on the line 'I-l of Figure 6.

Figure 8 is an elevation of one form of the bimetallic stri-p.

Figure 9 shows the strip in side View in normal condition and also flexed.

Figures 1G to 12 are vertical sections of the cut-out, in set position, provided with another form of reiease, taken respectively on the line Ill-I0 of Figure ll, the line II--II of Figure 10 andthe line i2-l2 of Figure 10.

igures 13 and 14 are views of another form of the bimetallic strip, shown respectively in elevation and formed into a helix.

The cut-out comprises a base 2 of insulating material supporting the mechanism which is protected by a hood 3 also of insulating material. This hood is iixed on the base by screws 4. The main frame 5, reinforced by a web E supports the parts associated with the moving Contact I5 and a terminal 'l screwed into an angle bracket 8 (Figure 3), the yterminal and bracket both being insulated electrically from the frame 5.

A `bifurcated bimetallic s-trip 9 controlling the operation of the cut-out is secured by screws II to the 4frame 5 to which is electrically connected one of its limbs while the other limb, insulated from the frame is connected to the angle-bracket 8, that is to the terminal l. At its end the bimetallic strip carries an insulated knob I2 abutting against a latch `blade I3.

One end of a blade lil is anchored to the frame 5 by a spring I5 consisting of several leaves of small thickness which afford it greater flexibility and robustness. To its other end is secured a spring tongue l? carrying the moving contact I5. A latch roller I8 pivots on a spindle pressed in the `blade i4 (Fig. 2).

A Ipush rod I9, for example of rectangular section, slides in the upper part of the frame 5 and `is guided at its lower end by a guide 20 fixed to the base of the frame 5.

The latch blade I3 is pivoted by its upper end 22 to `the rod or lpillar i9 at 2i in a groove 23 in which it is housed, a spring 24 urging it out of the housing groove so :that it retains the blade I4 when the cut-out is set by engagement of :the roller I8 in a notch 31 of blade I3.

When the cut-out is set, a pawl 2B urged by a spring 25 engages a notch in the Ipush rod I9 and so holds the latter in its innermost position; the push rod I9 terminates in a setting press-button 2l.

A release button Z8 subjected to a return spring 29, can act upon the end of -a lever 3i pivoted on the same pin 36 as Ithe pawl 26, the other end of the lever 3| being positioned to co-act with the tail of the pawL The second terminal 32 h-olds rto the base 2 (Figure 1) a block 33 of insulating material about which is a winding 34. A magnetic core 35 -passes through the block 33 and carries the fixed contact 36. One end of the winding 34 is connected to the terminal 32 and its other end to the contact 36 through the magnetic core 3 5.

The terminals 'I and 32 can be in the form of slotted pins as shown in Figures 1 and 3, of standard diameter and spacing, or in the form of spring contacts, or of any other form adapted to carry the current.

The operation of the cut-out is as follows:

When it is set (Figures 1 and 2), the current entering for instance at terminal 'I passes through the angle bracket 3, then in succession through the two limbs f the strip 9, the spring I6, the blade I4, the moving contact I5, the iixed contact 36, the winding 34 and the second terminal 32.

The cross-section of the two limbs of the strip is made such that it can carry the norrninal current without noticeable deflection. When the current rises above predetermined value, the strip deflects under the heating effect and its end 9a, through the insulated knob I2 pushes the latch blade I3 into the housing in the push rod I9 (Figure 2).

The roller I8 leaves the notch 3l of the blade I3 and, the blade I4 being released, immediately obeys its spring I6, so violently withdrawing the moving contact I5 from the fixed contact 35.

The upper end of the contact I5 then strikes the tail end of the pawl 26, which accordingly releases the push rod I9.

The Spring 38 encircling the guide 2l! raises the push rod which assures its released position (Figure 3) In this position the roller I8 on the blade I4 lodges again in the notch 3l in the blade I3.

In this illustrated form of construction of the cut-out, the button 26 enables the cut-out to be operated without application to it of an excessive current. The button 28 acts on the end of the lever 3| which rocks and with its other end disengages the pawl 26 from the push rod I9 which is pushed outward by its spring 38, so releasing the blade I4 carrying the moving contact I5.

. To re-set the cut-out it is only necessary fully to depress the button 2l, thus depressing the blade I4 through the agency of the latch blade I3, and loading the spring I6 and the spring 38 encircling the guide 26. The pawl 26 under the action of its spring 25 locks the push rod I9 in its innermost position and the cut-out is again in its set position (circuit closed).

The bent form of the blade I4 enables the axis of the roller I8 to be exactly perpendicular to the edge of the notch 3l in the blade I3. This important condition ensures reliable operation of the roller without lateral friction.

Accor-ding to the nominal current, the contacts can be constructed in various ways to ensure maximum eiectiveness and minimum wear of the device.

Figures 1 to 3 show a type of contact suitable for very low currents. In this case, the bimetallic strip, necessarily of small section would be rapidly damaged by the heavy current resulting from a dead short circuit, if no special provision were made.

'I'he winding 34 in series with the Strip 9 has a two-fold purpose;

a. It is constituted by a wire of high resistivity and high melting point, of heavy enough section not to have noticeable resistance when carrying the nominal current. But in the case of a short circuit its resistance is suilicient to limit the current. In this way it protects the bimetallic strip until release, which is practically immediate, is completed.

b. It forms the winding of an electromagnet, the magnetic flux of which passing through the contact-carrying core 35, assists in blowing out the arc at break. The contact 36 can be of carbon to avoid welding together of the contacts at break.

Other forms of contact can be provided for higher currents.

Figures 4 and 5 relate to an arrangement of multiple contacts. The multiplication of the contacts reduces the heating eect for the same equivalent total surface and it ensures better.

maintenance of the surfaces in contact.

Further, the arrangement shown comprises principal contact 4I and 42, 43 and lid, of metal, and auxiliary contacts 45 and 46. The contact l5 of carbon, is movable. This enables the break to take place in two stages.

l. When the blade I4 rises the break takes place in the rst stage at the principal, metal contacts II and 32, .13 and dll. The contact 45 however, lifted by a spring 4l, moves with the movable contact I3 until the contact carrier 48 reaches its highest position. During the very short time during which the contact 45 is moving, the whole of the current passes through it and the metal contacts eli and 42, 43 and 44 separate without the formation of an arc.

2. When the contact 46 leaves the contact 45,

fthe arc is produced between metal and carbon surfaces, thus avoiding the risk of welding t0- gether. The carbon contact 65 is connected to a plate 49 and so to the terminal 32, by a flexible lead 5I providing for the passage of current between these parts.

Figures 6 and 7 show a modication of this arrangement.

The contacts I5 and 46 are identical with and have the same purpose as those described above.

The principal, metallic contacts 52 and 56 instead of being fixed like the contacts 4I and 43, are movable about an axis 53 and rise slightly at break under the action of springs 54 and 55. This rise ensures a slight sliding of the cylindrical surface of the contacts 52 and 56 on the contact 5l. This sliding cleans the surfaces of the contacts and the break does not take place at the same points as does the passage of current during service.

It is to be noted that the pressures on the contacts 52 and 55 are equalised because the contact 5I can rock on the rivet 58 which secures it to the blade I4 and the spring I5 tends to push spring 59 abutting a support. 6! carried by a distance-piece 62. The button also carries a ramp 63 having an inclined prole which as it moves inwards causes a lever E5 pivoted on the dist ncepiece 62 to rock in the direction of the arrow; 5 64 (Figure 11).

The end 66 of this lever 65 accordingly in the direction of the arrow 6'! below the 1 axis 68 of the latch blade I3 (Figure pushing the latter into its housing in the pus rod I9, the wall of the notch 31 running o.; thV roller I8 to release the blade I4 which rises, s opening the circuit at the contacts of 'the cutout.

To obtain a cut-out able to control very low currents, of the order or one ampere or less for example while holding the device within smali limits of size, the width and thickness or^ the limbs of the bimetallic strip must be reduced, because it is the cross-section of this strip which de 20 mines the nominal current of the cut-out, as the fragility of the limbs increases proportion-- ately with the reduction of the cross-section, the mechanical effort of which the strip capable is also limited accordingly.

To increase substantially both the mechanical eiTort developed and the actual ohmic the bimetallic strip 69 (Figures 10, l2 and ifi) can be formed into a helix in such a way th strip is obtained having the same dimension in 30 length as the strip 9 of Figure 1.

The deflection is no longer a bend by Figure 9, but a twist as indicated. by the 1I in Figure 14. This possibility oi' ob* an increase in the eiiort exerted by the s' in its resistance, for a given current enab cut-out to be constructed releasing at lower currents than in the case of cut-outs of the same bulk having a straight bimetallic strip as shown in Fig. 8.

The operation of the cut-out shown in Figures 10 to 12 is as follows:

The whole current passing through the bimetallic strip causes heating of its turns 'i2 and when the current exceeds the nominal value, the turns tend to wind tighter to a substantiai gree. The free end 'iii of the helix accordi f acts on the latch blade I 3 which releases the blade I4. For satisfactory operation and to avoid any bending, it is necessary that the turns 'i2 should bear against the hood 3.

The advantages of the cut-out according to the invention, which is adapted to be used to replace fusible cut-outs are:

1. A very small bulk enabling it to be used commerical fuse bases, whether of the type i sockets for pins, for spring contacts, or ior per manently mounted fuse-holders;

2. A very high sensitivity of operation con-- sequent upon the combination or three features:

(a) Instantaneous heating of the bimetailic controlling strip by the direct transmission oi the current through it.

(b) Reduction of the eiort necessary for operation by the use of a latch blade in the form of a lever on which the strip acts,

(c) Unlatching effected by the action of a small roller, thus without any sliding friction;

3. Ease of resetting and the tamperfriese of a device actuated by a re-setting press-button easily accessible even if the cut-out is sealed to its base.

The separation of the contacts being indepenN dent of the release of the member carrying the resetting press-button, the operation of the cut- 6 out is ensured even if the press-button is deliberately blocked in the re-setting position;

4. Considerable separation of the contacts, facilitating extinction of the arc when the cut-out operates, the extinction of the arc being further facilitated by blow-out devices varying according to the designed nominal current.

5. The resistance of the device to dead shortcircuits consequent upon its high sensitivity which ensures that it operates before heating due to a heavy overload can damage the parts.

6. The possibility of adding a release button which converts the device into a switch-cut-out. This arrangement is particularly valuable for built-in or base-plate installation on account of the very small bulk of the combined switch and cut-out.

7. Finally the very considerable space amiable for the contacts, permitting multiplication of the points of contact and the accommodation of arc extinguishing means as described above.

What I claim is:

l. An electric cut-out comprising a support, at least one contact piece carried rigidly by said support cooperating movable contact pieces, an at least partly yielding member carrying said movable contact pieces in front of the first contact piece, a transversal blade normally engaging last mentioned contact carrying member and holding it in its operative position, yielding means urging the transversal blade into its operative position, a heat sensitive member carried by the support, a pusher rod movably carried by the support and housing the transversal blade and associated yielding means, a catch and spring system holding the pusher rod in its depressed position in which the transversal blade engages the operative contact carrying member, means whereby the heat sensitive member, when heated, urges the transversal blade carried by the pusher member in depressed position against the action of its associated yielding means into its inoperative position, means whereby the contact carrying member when released with rererence to the transversal blade enters its inoperative position and acts on the catch and spring system for releasing the pusher member, a spring urging the pusher member into its outermost position in which the transversal blade carried by said pusher member reengages the contact carrying member in its outer released inoperative position.

2. An electric cut-out comprising a support, at least one contact piece carried rigidly by said support, cooperating movable contact pieces, an at least partly yielding member carrying said movable contact pieces in front of the rst contact piece, a transversal blade normally engaging last mentioned contact carrying member and holding it in its operative position, yielding means urging the transversal blade into its operative position, a heat sensitive member carried by the support, a pusher rod movably carried by the support and housing the transversal blade and associated yielding means, a catch and spring system holding the pusher rod in its depressed position in which the transversal blade engages the operative contact carrying member, means whereby the heat sensitive member, when heated, urges the transversal blade carried by the pusher member in depressed position against the action of its associated yielding means into its inoperative position, means whereby the contact carrying member when released with reference to the transversal blade enters its inoperative position and acts on the catch and spring system for releasing the pusher member, a spring urging the pusher member into its outermost position in which the transversal blade carried by said pusher member reengages the contact carrying member in its outer released inoperative position, a releasing knob, a leverage controlled thereby and adapted to act in the position obtained by depression of the knob on the catch acting on the pusher member in antagonism with the catch spring for releasing the pusher member, the displacement of the pusher member under the action of its spring moving the transversal blade with it and shifting therewith the contact carrying member into its inoperative position.

3. An electric cut-out `comprising a support, at least one contact-piece carried rigidly by said support, cooperating movable contact pieces, a further movable contact piece, an at least partly yielding member carrying all said movable contact piece in front of the rst contact pieces, a normally stationary carbon contact piece of same polarity as the rst mentioned contact piece, means whereby the carbon contact-piece is adapted to .continue feeding current to the corresponding movable contact piece during a short period after the breaking of the circuit through the first-mentioned stationary contact piece, a transversal blade normally engaging last mentioned `Contact carrying member and holding it in its operative position, yielding means urging the transversal blade into its operative position, a heat sensitive member carried by the support, a pusher rod slidably carried by the support and housing the transversal blade and associated yielding means, a vcatch and spring system holding the pusher rod in its depressed position in which the transversal blade engages the operative contact carrying member, means whereby the heat sensitive member, when heated, urges the transversal blade carried by the pusher member in depressed position against the action of its associated yielding means into its inoperative position, means whereby the contact carrying member when released with reference to the transversal blade enters its inoperative position and acts on the catch and spring system for releasing the pusher member and a spring urging the pusher member into its outermost position in which the transversal blade carried by said pusher member reengages the contact carrying member in its outer released inoperative position.

4. An electric cut-out comprising a support, at least one contact piece carried rigidly by said support, cooperating movable contact pieces, an at least partly yielding member carrying said movable contact pieces in front of the rst contact piece, a transversal blade normally engaging last mentioned contact carrying member and holding it in its operative position, yielding means urging the transversal blade into its operative position, a bi-metallic heat sensitive strip member carried by the support, a pusher rod slidably carried by the support and housing the transversal blade and associated yielding means, a catch and spring system holding the pusher rod in its depressed position in which the transversal blade engages the operative Contact carrying member, means whereby the heat sensitive member, when heated, urges the transversal blade carried by the pusher member in depressed position against the action of its associated yielding means into its inoperative position, means whereby the contact carrying member' when released withreference to' the tiansvr'sai' blade enters its inoperative position and acts on the catch and spring system for releasing the pusher member, a spring urging the' pusher" member into its outermost position in which the transversal blade carried by said pusher mem'- ber reengages the contact carrying member in its outer released inoperative position.

5. An electric cut-out comprising a support, atv least one contact-piece carried rigidly by said:

support, cooperating movable contact pieces,l a further movable contact-piece, an at least partly yielding member carrying all said movable contact pieces in front of the rst contact piece, a;

normally stationary carbon contact piece of same polarity as the rst mentioned contact piece adapted to move between its operative position in which it lies in the plane of the first mentioned stationary contact piece and a current breaking position in which it lies nearer the cooperating further movable contact piece than the rst mentioned stationary contact piece With reference to the corresponding movable contact pieces, a spring urging the carbon contact-piece towards the corresponding further movable contact-piece, a transversal blade normally engaging last mentioned Contact carrying member and holding it in its operative position, yielding means urging the transversal blade into its operative position, a heat sensitive member carried by the support, a pusher rod slidably carried by the support and housing the transversal blade and associated yielding means, a catch and spring system holding the pusher rod in its depressed position in which the transversal blade engages the operative Contact carrying member, means whereby the heat sensitive member, when heated, urges the transversal blade carried by the pusher member in depressed position against the action of its 40 associated yielding means into its inoperative position, means whereby the contact carrying member when released with reference to the transversal blade enters its inoperative position and acts on the catch and spring system for releasing the pusher member and a spring urging the pusher member into its outermost position in which the transversal blade carried by said pusher member reengages the contact carrying member in its outer released inoperative position.

6. An electric cut-out comprising a support, associated rockable rounded contact pieces of same polarity, a pivot rigid with the support for said contact pieces, cooperating movable contact pieces, an at least partly yielding member carrying said movable contact pieces in front of the rst contact pieces, springs urging the rockable contact pieces to move round their pivots towards the corresponding movable contact pieces to contact therewith through a substantially large frictional area, a transversal blade normally engaging last mentioned contact carrying member and holding it in its operative position, yielding means` urging the transversal blade into its operative` v position, a heat sensitive member carried by the support, a pusher rod slidably carried by the support and housing the transversal blade and associated yielding means, a catch and spring system holding the pusher rod in its depressed position in which the transversal blade engages the operative contact carrying member, means whereby the heat sensitive member, when heated, urges the transversal blade carried by the pushermember in depressed position against the action of its associated yielding means into its inoperative position, means whereby the contact carrying.,

member when released with reference to the transversal blade enters its inoperative position and acts on the catch and spring system for releasing the pusher member, a spring urging the pusher member into its outermost position in which the transversal. blade carried by said pusher member reengages the contact carrying member in its outer released inoperative position.

'7. An electric cut-out comprising a support, at least one Contact piece carried rigidly by said support, cooperating movable contact pieces, an at least partly yielding member carrying said movable contact pieces in front of the rst contact piece, a transversal blade normally engaging last mentioned Contact carrying member and holding it in its operative position, yielding means urging the transversal blade into its operative position, a heat sensitive member carried by the support, a pusher rod slidably carried by the support and housing the transversal blade and associated yielding means, a catch and spring system holding the pusher rod in its depressed position in which the transversal blade engages the operative contact carrying member, means whereby the heat sensitive member, when heated, urges the transversal blade carried by the pusher member in depresssed position against the action of its associated yielding means into its inoperative position, means whereby the contact carrying member when released with reference to the transversal blade enters its inoperative position and acts on the catch and spring system for releasing the pusher member, a spring urging the pusher member into its outermost position in which the transversal blade carried by said pusher member reengages the contact carrying member in its outer released inoperative position, a releasing depressable knob on the support, an antagonistic spring acting on said releasing knob l0 and mechanical means whereby the depression of the knob urges the transversal blade against the action of the yielding means for releasing the operative contact carrying member.

8. An electric cut-out comprising a support, at least one contact piece* carried rigidly by said support, cooperating movable contact pieces, an at least partly yielding member carrying said movable contact pieces in front of the first contact piece, a transversal blade normally engaging last mentioned Contact carrying member and holding it in its operative position, yielding means urging the transversal blade into its operative position, a spirally twisted bi-metallic strip member carried by the frame at one end and the free end of which is adapted to move under the action of heat, a pusher rod slidably carried by the support and housing the transversal blade and associated yielding means, a catch and spring system holding the pusher rod n its depressed position in which the transversal blade engages the operative contact carrying member, means whereby the bi-metallic member, when heated, urges the transversal blade carried by the pusher member in depressed position against the action of its associated yielding means into its inoperative position, means whereby the contact carrying member when released with reference to the transversal blade enters its inoperative position and acts on the catch and spring system for releasing the pusher member, a spring urging the pusher member into its outermost position in which the transversal blade carried by said pusher member reengages the contact carrying member in its outer released inoperative position EMILE ANDR BERTHIER..

No references cited.

Images