Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H3/00—Mechanisms for operating contacts
  • H01H3/001—Means for preventing or breaking contact-welding

Definitions

• the invention relates to an electrical switch comprising in a housing:
• - Forced opening means which are arranged between one end of the pusher and the contact bridge to be opened in the working position of this pusher and which transmit forces directed in the direction beyond this position and to this bridge. opening when the movement of the pusher and / or the neutral device has not caused opening.
• Such switches are systematically used in control and command circuits where the opening of protection circuits by means of abrupt opening and closing contacts with and positive opening is imperatively requested by the security services or recommended by specific standards.
• the actuation stroke strictly necessary to operate, in new condition, a tilting of the devices passing through neutral, and therefore the change of state of the two switches. , is relatively small and would have no reason to be chosen differently if the contacts kept their dimensions, if no mechanical member was exposed to a certain wear or rupture, and if the pads of the contacts rest, which must open in the working position, were not likely to be welded at the time when such an opening is essential.
• the invention therefore proposes to provide an electrical interrup ⁇ tor having the general constitution men ⁇ tioned above and which, thanks to new measures, are able to replace a previous model, without requiring change, or the modification of the previous transmission device, and while meeting the recommendations which relate to increasing the distance of forced separation of the rest contacts.
• the aim is achieved thanks to the fact that the first mobile bridge, which opens its first contacts in the working position of the pusher and the second mobile bridge which closes its second contacts in the same position, are connected by a device d hitch establishing between them longitudinally a connection using, on the one hand, compressible parts, such as springs, which are in initial compression in normal operation and which receive additional compression at the time of the forced opening of the first contacts and, on the other hand, non-compressible drive means acting in the opposite direction to the springs when the second contacts open.
• compressible parts such as springs
• FIGS. 7a, 7b two partial half-views in longitudinal section and in the rest position respectively in the limit position of a switching device in which the forced lifting of the rest contact bridge is operated using cams, pinions and racks;
• An electrical switch 1 visible in FIG. 1 and in accordance with the invention, comprises an insulating box 2 inside which a control pusher 3 of the two transverse and symmetrical contact bridges 4 moves longitudinally along XX ′ and 5 between a rest position R illustrated on the left half, and a working position T illustrated on the right half, see Figures la and lb.
• FIG. 6 illustrating a prior device 50 fitted with a switch 53 housed in a body 54 with which a transmission head 52 is associated, which is capable of transmitting the movements of a lever 55 to the pusher 51 via a rotary cam 56 and a rocker arm 57.
• a first contact bridge 4 the movable contact pads of which are applied to the fixed contacts 5, 6 in the R posi ⁇ tion by two neutral-passage devices 7, 8 symmetrically arranged with respect to the axis XX 'longitudi ⁇ nal, is arranged in a lower region 11 of the pusher and in the vicinity of two safety levers 9, 10 which are placed symmetrically on either side of this pusher and pivot around parallel and fixed transverse axes.
• Each point-passing device such as 7, 8 comprises, in a known manner, a helical trigger spring, working in compression such as 12, the opposite ends of which are compressed by two stirrups 13, 14 each having a notch such as 15, 16 .
• the two opposite notches of a particular device which are placed in the axis YY 'of the corresponding spring, are permanently supported on two edges such as 17, 18 respectively 27, 28, each belonging 17, 18 to the pous ⁇ evening 3, and the others 27, 28 to an insulating mobile assembly 20 which can be moved longitudinally in the housing, see also Figures 1, 2, 3 and 5.
• the stirrups take one, 61, the shape of a cup 62 which surrounds the spring 12 to receive the 'one of its ends and has a central column 63, and the other, 64, the shape of a sheath 65 having a support flange 66 for the other end of the spring and a bore 67 capable of receiving and guiding the column 63.
• This movable element 20 is integral in its lower part with the first contact bridge 4 and has two parallel longitudinal columns or partitions 21, 22 which are directed towards and extend above the second contact bridge 5 ; the latter, which is separate from the fixed contacts 23, 24 placed opposite when the pusher is in the rest position R, must be applied to these when the pusher reaches its working position T, while the first bridge must be separate from fixed contacts 5, 6.
• the mobile equipment 20 advantageously takes the form of a case or frame which is open at the two longitudinal ends, and which has an internal housing 60 in which the pusher 3; the latter, as well as the safety levers, are guided in the housing along guide surfaces 68, respectively of pivots 69, the presence of which is only partially shown.
• the moving element 20 is itself guided by interior surfaces of the housing.
• edges 27, 28 which are placed closer to the second movable bridge 5 than to the first, are also located in the vicinity of helical transmission springs 25, 26 resting symmetrically, on the one hand, on lower surfaces of the second bridge, which are directed towards the first bridge and, on the other hand, against bearing surfaces 29, 30 belonging to the moving element 20.
• the axes of these springs are parallel to XX ′.
• This equipment 20 also has two cross-hooks 31, 32 which are arranged above portions of upper surfaces 33, 34 of the second bridge and in the vicinity of the movable contact pads 35, 36. As long as the first contact bridge is not retained on its fixed contacts by accidental welding, the members which have just been described are sufficient to ensure normal operation when the pusher moves between the R and T positions, to operate openings and closings of the two contact bridges.
• the passive ends 40 are completely engaged in a transverse groove 42 of the pusher at least as long as the latter evolves between the positions R and T, and gradually emerge from this groove when the pusher evolves between the position T and the position L.
• the distance which then separates the fixed and movable contact pads from the second bridge is approximately one and a half times greater than that which would result from normal opening, without using the means which have just been described.
• a prior safety switch device 50 the operating parameters of which are given by way of example, and the constitution of which is shown diagrammatically in FIG. 6, the total stroke of the pusher 51 given by the transmission head to cam 52 between positions R and L, is approximately 7.2 mm, and the separation distance of the contacts of the anterior switch 53 was approximately 0.8 mm, that this operation was obtained during a normal opening, or during a forced separation of the contacts.
• this separation distance is brought to 2 mm both in normal opening regime and in opening regime forced, when the pusher moves from position R with a stroke of 5.1 mm.
• the ratio between the anterior travel of the movable opening contact bridge and the amplitude of the movement provided by the anterior cam device was therefore close to ten.
• the ratio between this stroke and this amplitude is between three and four, which represents an advantageous property which is notably conferred by the presence of a transverse groove for driving the safety levers.
• the safety levers constantly cooperate with guide surfaces and, possibly, using application forces, this which saves them from uncontrolled movements likely to disturb the movements of the first contact bridge.
• the profile of the cams can advantageously be studied so that the stroke, respectively the force communicated to the contact bridge with opening 4 'follow a particular law; this transmission is established with a precision much higher than that provided by levers, due to the large angular travel that can be given to the pinions; the elasticity provided by the springs such as 25, 26 is not necessary here to restore the reverse movement of the ca es, when the pusher resumes its rest position.
• the cams can then exert their forces at points 84, 85, of the locally widened bridge 86, which are close to the contacts a_ t

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Publications (1)

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Citations (6)

• 1985
  • 1985-03-13 FR FR8504069A patent/FR2579009B1/fr not_active Expired
• 1986
  • 1986-03-12 WO PCT/FR1986/000079 patent/WO1986005627A1/fr active Application Filing
  • 1986-03-12 GB GB8626025A patent/GB2182495B/en not_active Expired
  • 1986-03-12 DE DE19863690115 patent/DE3690115T1/de active Pending
  • 1986-03-12 DE DE3690115A patent/DE3690115C2/de not_active Expired - Fee Related
  • 1986-03-12 IT IT19716/86A patent/IT1188429B/it active
  • 1986-11-04 SE SE8604716A patent/SE450921B/sv not_active IP Right Cessation

Patent Citations (6)

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