US2695939A - Electric switching device - Google Patents

Description

Nov. 30, 1954 R. FILLIETTE ELECTRIC SWITCHING DEVICE 3 Sheets-Sheet l Filed June 17. 19,52

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ELECTRIC SWITCHING DEVICE Filed June 17. 1952 3 Sheets-Sheet 2 Nov. 30, 1954 Filed June 1'?. 1952 R. FILLIETTE ELECTRIC SWITCHING DEVICE 3 Sheets-Sheet 3 United States Patent ELECTRIC SWITCHING DEVICE Raymond Filliette, Rueil-Malmaison, France, assignor `to :La Tlmcanique Electrique (Socit Anonyme), Seine, France, a French company paratus, such as contactors'and circuit breakers, for example for the control of hoists and lifts, controllers for y.the .control of auxiliary circuits and all -such apparatus having a large number of contacts.

According to the invention an `electric switching device comprisesa lever connected to a current lead-in terminal, which lever is adapted to move between two opposed fixed contacts, and is freely mounted upon and maintained by spring pressure against a fixed bearingmember forming a pivot, and against one of the twoaforesaid contacts,.the pivoted movement of the lever necessary for changing over from one contact to the other being effected by. mea-ns of a thrust member or other known externally operated -rnechanical device, a blade or other free element being .interposed betweenthe said thrust member and the said Jever and -maintained by spring pressurey against the said .leverat a'point close to the support or pivot of the said lever.

In one 4embodiment of the invention, the spring pressure by which the lever is maintained against its pivot :and the spring pressure by which the blade is maintained against the lever are effected by a single spring acting on thesaid blade, the latter bearing againstfthe lever at at .least two pointssituated on either'side of the said pivot.

' The relative position of the different bearing, pivoting vand contact points is determined in such manner lthat the contact pressure of the lever upon eitherfof the freed con- `.tacts is substantially the same.

' The blade freely mounted and maintained against the `lever by spring pressure imparts to the latter a certain independence with respect to the thrust member.

In particular, when the lever abuts against the fixed off-normal contact under the action of the thrust member the move- 4ment of the thrust member can continue without causing any shock to or deformation of, the electrical conducting -parts ofthe device. The provision or the blade forming a transmission member between the thrust member andthe lever permits a certain amount of lost motion.

'The tension of the spring by which theblade is applied against the lever maybe adjustable, for example by means of a nut forming an abutment at one end of the said spring. This permits of adjusting'the contactpressure while at the same time maintaining the lever firmly applied against its support. This pressure once adjusted, is substantially unsusceptible to appreciable variations, even after a very large number of operations. Nevertheless, if necessary, such variations as may occur may be readily compensated by adjusting the regulating screw. The switching device according to the invention thus affords an appreciable advantage over switching devices comprising a flexible blade which is submitted to successive deformations which are likely to modify its mechanical characteristics and consequently the contact pressure.

IThe Vbearing member on which the lever pivots is directly connected to the current lead-in terminal. The lever is thus permanently connected to the said terminal .through a good contact which is ysubjected to practically only negligible friction, whereby a long useful life of the *t* .device isensured. In addition owing to the fact that the lever is applied against the member by springfpressure, yany play is automatically taken up.

The various parts of the switching device are mounted inaccordance with the invention, on a base of insulating material which is of rectanglllarv shape. and of reduced -mounted on the base 1. The said depth, this being possible owing to the very limited width t large number of such devices in a limited space, so that electrical control arrangements of limited dimensions can be provided.

Finally, since the various parts are subjected to limited corcesand practically negligible friction, they may be nade of material requiring no especial mechanical propertes.

The present invention also includes electric control apparatus comprising switching devices of the type hereinbefore described.

In the accompanying drawing there is shown by way of ynon-limitative example, one embodiment of the invention as applied-to a unipolar reversing switch unit. In the drawing:

Figs. l, 2 and 3 are vertical sections through the unipolar reversing switch unit, showing the three operating positions thereof, and

Fig.-4 is a front elevation showing a plurality of switch unitsl arranged in juxtaposition.

Figs. 5 and 6show diagrammatically two modifications of the switch unit.

The switch units illustrated in the drawing comprise a-base 1 ofinsulating. material, preferably moulded, which Ais normally supported by a steel bar 2 on which it is secured by means of a strap 3 and nuts and bolts 4.

A :rod 5 provided with a current lead-n terminal 5a andhaving secured thereto a bearing member 6 provided with a knife edge, and tworods 13 and 15 provided with current leadfout terminals 13a and 15a and provided with studs :12and 11 respectively, forming fixed contacts are studs and the bearing member are preferably of silver. The rod 15 is connected to a-bent over arm 14 which is so arranged that the studs 11 and 12 lie opposed one to the other.

The movable contact of the switch comprises a lever 8 having lat one end,` on its opposite faces and at the level of the-studs 11 and 12 two contactmembers 9 and 10. The said lever is also provided with a raised portion 7 intended lto cofoperate with the bearing member 6 and, on the face opposite the said portion two studs 8a and 8b situated von either side ofthe portion 7, the stud 8a being positioned yadjacent'thereto. The portion 7 and the contact members 9 and v10 are preferably made of silver, while the studs .8a and 8b may consist of treated or case hardened steel.

The lever 8 is maintained against the bearing member 6 Aby a bladev 16 pressed against the studs 8a and 8b by stituting the axis ofthe extension 5b, while they are free to movey angularly with respect thereto.

Thetline B, parallel to the axis A and passing through the bearing. 6,-isV positioned at a distance from the axis A,vwhile thelines C and D extending through the points at which the bladeV 16 is applied against the lever 8 are pocslitioned respectively on either side of the axes A an B.

The. switch V.is-adapted to be mechanically actuated, for example in the case of a contacter, by an adjustable thrust member 19 mounted on an arm 2i) fixed on a shaft 2Il.by means of a strap 22 and screws 23. The thrust member 19is. adapted to act on the blade 16 in a direction indicated bythe line E, which is relatively remote from the line B extending through the bearing 6. It will be understood that the thrust member could be replaced by a cam, a dog or any other similar mechanical device.

The contact ,membersand the movable members `of the switch are disposed in a groove or recess formed in the face of the base and of sulcient depth to prevent any substantial lateral movement of the movableparts and to avoid any accidental contact with the adjacent switch units.

The switch operates in the following manner:

In the inoperative position (Fig. l), the thrust member 19 is free from engagement with the lever 16 which, under the action of the pressure set up by the sprlng 18 causes the blade 8 to pivot so that the Contact member 9 engages the stud 11.

Rotation of the shaft 21 through a certain angle causes the thrust member 19 to act on the lever 16 and the contact member 9 is thus withdrawnfrom the stud 11 (Fig. 2), thereby breaking the circuit connected to the terminals 5a and 15a.

Further rotation of the shaft 21 and the correspondlng displacement of the blade 16 and lever S, causes the contact member to bear against the stud 12, thereby closing the circuit connected to the terminals 5a and 13m Fi 3 rfighe r)elative position of the various lines B, C, D and E is such that the contact pressure between the contact member 9 and the stud 11 (Fig. l) is substantially the same as the contact pressure between the Contact member 10 and the stud 12 (Fig. 3). It is to be noted, in the latter ligure, that any movement of the thrust member 19 beyond the position of the lever 8 in which the contact 10 bears against the stud 12 causes the blade 16 to pivot on the stud 8a against the action of the 0 spring 18. Thus, owing to the flexible manner in which the blade 16 is mounted, the thrust member does not produce any shock which might cause damage to the parts of the switch.

As has hereinbefore been stated, the switch is in the form of a small unit adapted to be mounted in juxtaposition (see Fig. 4) in a small space with other similar units mounted on a common bar 2 Each unit has a separate mechanical actuating device. These devices may be independent of one another or associated with one another.

The blade 16 may be turned about the rod 5b so as to bring it into the position shown at 24 (see Fig. 5), the thrust member then being positioned at 25 and acting in a direction indicated by the line E. It will be understood that the blade 16 as shown in the drawing could comprise an extension as indicated at 24a (see Fig. 6), in which case the blade would extend from the line E to the line E'. In fact, only the relative position of the studs 8a and 8b is important, the form and the dimensions of the blade 16 being purely arbitrary.

In addition, the action of the thrust member may be exerted tangentially on the blade 16 instead of being exerted perpendicularly thereto, this being rendered possible due to the sloping form of the said blade. an arrangement would permit of the continuous rotation of the shaft 21, on which a number of arms 20 corresponding to an equal number of switch units may be fixed, the said arms being keyed in well-defined relative angular positions. In such a case, in order to reduce the friction of the thrust member on the blade, the thrust member or the blade may be provided with a roller. Such an arrangement is particularly advantageous in the case of controllers such as those employed for the operation of hoists and lifts.

It will be understood that modifications may be made to the switch unit hereinbefore described, by substitution of equivalent technical means, without departing from the scope of the present invention. In particular, the blade 16 could be replaced by any desired resilient member secured to the lever 8, for example at the point 8a, the spring 18 then bearing directly against the lever, for example at the point 8b.

What I claim is:

1. In an electric switch assembly adapted to connect and disconnect a pair of circuit terminals, fulcrum means electrically connected to one terminal, a rigid electrically conductive lever movable about said fulcrum between two positions, a contacting point on the lever spaced from said fulcrum adapted respectively to engage and disengage the other terminal in the two positions of the lever, means for applying spring pressure to the lever at a pair of spaced points thereof located to either side of said fulcrum for normally maintaining the lever in one position, and means for increasing the pressure Such applied to the lever at that one of said pair of spaced points which is located between the fulcrum and said contacting point over the pressure applied to the lever at the other of said spaced points, in order to bring the lever to its other position.

2. An electric switch assembly as claimed in claim 1, wherein the first mentioned one of said pair of spaced points is substantially closer to said ulcrum than is the other one of the spaced points.

3. An electric switch assembly as claimed in claim 1, wherein the first mentioned one of said pair of spaced points is located in immediate proximity to said fulcrum, and the other one of said spaced points is spaced a considerably greater distance from the fulcrum.

4. In an electric switch assembly adapted for establishing at least two different conditions of an electric circuit, a stationary support, fulcrum means fixed to said support, a rigid lever movable about the fulcrum between two positions in each of which a respective'one of said circuit conditions is established, spring means for applying pressure to the lever at a pair of spaced points thereof located on either side of the fulcrum for normally maintaining the lever in one position, and mechanically actuating means for displacing the lever to its other position against the action of said spring means.

5. An electric switch assembly as claimed in claim 4, wherein said fulcrum is electrically connected to one circuit terminal, and said lever is electrically conductive and in one of its said positions is adapted to have a contacting point thereof engage another circuit terminal.`

6. An electric switch assembly as claimed in claim 4, wherein said fulcrum is electrically connected to one circuit terminal, and said lever is electrically conductive and in one of its said positions is adapted to have a contacting point thereof engage another circuit terminal, and in its other said position is adapted tohave its said contacting point disengage said other circuit terminal and have a further contacting point thereof engage a further circuit terminal.

7. An electric switch assembly as claimed in claim 4, wherein said fulcrum is electrically connected to one circuit terminal, and said lever is electrically conductive and in one of its said positions is adapted to have a contacting point thereof engage another circuit terminal, and wherein said mechanically actuating means acts to increase the pressure applied to the lever at that one of said spaced points thereof which is located between said fulcrum and 4said contacting point.

8. In an electric switch assembly adapted for selectively establishing at least two different conditions of an electric circuit, fulcrum means, a substantially rigid lever movable about said fulcrum between two positions in each of which a respective one of said circuit conditions is established, a pressure-transmitting member engaging said lever at spaced points thereof lying on either side of said fulcrum, a spring acting on said member for applying pressure therethrough to both said spaced points of thelever normally to maintain the lever in one of its said positions, and an actuating element for selectively actuating said member to bring the lever to its other position.

9. An electric switch assembly as claimed in claim'8, wherein said spring is adjustable.

l0. In an electric switch assembly adapted for selectively connecting a irst circuit terminal to either one of two other terminals, a furcrum element electrically connected to said lirst terminal, a rigid electrically-conductive lever movable about said fulcrum between two positions, adjacent contacting points on opposite faces of the lever spaced from said fulcrum and adapted to make contact with respectively related ones of said terminals in each of said lever positions, a pressure-transmitting member engaging said lever at two spaced points thereof on either side of said fulcrum, said member being spaced from said lever intermediate the points of engagement thereof with the lever for applying pressure therethrough to both said spaced points of the lever to maintain the lever in one of its said positions, said member having anl extension beyond one of said points of engagement thereof, and an actuating element adapted to engage said extension for selectively actuating said member to bring the lever to its other position. y

ll. A switch assembly as claimed in claim l0, wherein the relative spacings of said points and said fulcrum are so predetermined that the pressure developed between said contacting points and the related terminals in both positions of the lever is substantially the same.

l2. A switch assembly as claimed in claim l0, which comprises a mounting block of insulating material of narrow elongated generally rectangular form, and means for mounting said fulcrum, said pressure transmitting member and said spring means adjacent one end of the block and for mounting said other terminals adjacent the other end of the block with said lever extending therebetween along the length of the block for engagement with said fulcrum and said member and with either selected one of said other terminals under the action of said spring means.

13. A switch assembly as claimed in claim l0, which comprises a mounting block of insulating material of narrow elongated generally rectangular form, means for 15 2,517,052

mounting said fulcrum, said pressure transmitting member and said spring means adjacent one end of the block and for mounting said other terminals adjacent the other end of the block with said lever extending therebetween along the length of the block for engagement with the fulcrum and with said member and with either selected one of said other terminals under the action of said spring means, and means for mounting a plurality of similar blocks in transversely juxtaposed relationship.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Da te Swinehart Aug. l, 1950

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