EP0112258B1 - Electrical security socket, especially for an explosive atmosphere - Google Patents

Description

The present invention relates generally to so-called safety sockets, and more particularly relates to those of these sockets which are intended to be used in an explosive atmosphere.

As is known, the sockets, or, more generally, the connectors intended to connect electrically, and at will, two cables, comprise, on the one hand, a female part, or base, equipped , in addition to a possible earth cell, at least two phase or neutral cells each respectively electrically connected to the conductors of a first of these cables, and, on the other hand, a male part, or plug, fitted with pins , which, each respectively connected to the conductors of the second of these, are intended to be each respectively engaged in such cells, for the desired electrical connection.

In an explosive atmosphere, and for obvious safety reasons, it is important that the contact between pins and cells takes place in a suitably confined enclosure, commonly known as explosion-proof safety chamber, so that, if a spark occurs during such a contact, both when the current is established and when it is cut off, the explosion liable to result is limited to this safety chamber, without propagation of the corresponding flame outside of it.

To date, such a safety chamber is common to all of the cells of the base.

Several arrangements have therefore been proposed, all of which assume mechanical locking of the plug on the base.

According to a first of these provisions, a bayonet mount is provided between the plug and the base, and, more often than not, it is also provided therein, for example in a separate compartment, a switch, which, arranged upstream cells, systematically de-energizes them, so as to allow the extraction of the plug when the cells are thus de-energized, and, conversely, to prevent their introduction when these cells are energized.

According to a variant, which is in practice accepted by regulations only for sockets whose nominal current is less than 10A for 250V, there is no such switch, but a cover prohibited to the pins the plug direct access to the socket in the base.

Upon engagement of the plug, a rotation of the latter with respect to the base ensures, on the one hand, its mechanical locking on the latter, and, on the other hand, that is, in the first case, the closing of the switch implemented, that is, in the second case, the retraction of the cover controlling access to the cells of the base.

According to a second arrangement already known, a key is provided between the plug and the base, which controls the mechanical locking of this plug on this base, and which ensures, by acting simultaneously on a switch located in a compartment separate from the latter, establishing the current upstream of the cells, or cutting it off.

In practice, such arrangements lead to relatively complicated embodiments, requiring a switch or a cover combined with a mechanical locking device, and therefore relatively bulky and expensive.

Finally, according to a third known arrangement, in particular by American patent N US-A-4 192 572, in which the phase or neutral cell in which the pin of a plug must be engaged belongs to a piston which is mounted axially movable in a chamber having on its bottom a contact member, said piston dividing said chamber into two portions and having, at the front, said phase or neutral cell, it is systematically guaranteed to be extinguished by a gas from the arc arising from the disconnection of the plug, this gas then being released by a member provided for this purpose at the end of the spindle concerned.

This arrangement therefore requires the implementation of a plug provided with special pins and these are to be changed after intervention under load.

The present invention generally relates to a provision making it possible to avoid these drawbacks, and in particular allowing an automatic de-energization of the cells of the base during the separation of the plug, without the use of any switch or any cover, without mechanical locking device, and without the use of special pins for the plug.

More specifically, it relates to a base for a safety socket, in particular for an explosive atmosphere, of the type comprising, in a body of insulating material. for cooperation with the pins of a socket-outlet plug, in addition to a possible earth cell, at least one phase or neutral cell arranged in a chamber, with in said chamber, on the one hand, on the bottom of that - Here, a contact member, and, on the other hand, mounted axially movable, a contact piston, which divides said chamber into two portions and which. at the front, on the outlet side thereof, has the associated phase or neutral cell, this base being generally characterized in that the stroke of the contact piston in the chamber is made sufficient to that, when it is at the end of the front stroke, on the side of the outlet of said chamber, it is devoid of any contact with the associated contact member.

Consequently, when the plug is withdrawn relative to the base, the pins of the latter drive the contact pistons with the cells of which they are each respectively engaged, and, before they release themselves from these pistons of contact, they provoke, by the mere fact their own withdrawal movement, a clearance of these contact pistons vis-à-vis the associated contact members.

In other words, the withdrawal of a plug from a base according to the invention advantageously involves a double disconnection, namely, on the one hand, a disconnection between the contact pistons and the contact members present in the explosion-proof safety chambers corresponding, and, on the other hand, a disconnection of the pins of the plug relative to the contact pistons.

Thus, the security conditions to be observed are very simply ensured.

In practice, the base according to the invention comprises as many separate chambers as there are phase or neutral cells, with, in each one a contact piston having the corresponding phase or neutral cell, and it s 'These are explosion-proof safety chambers, that is to say chambers capable of confining a possible explosion.

Security conditions are reinforced.

In a particular embodiment, the contact member used in such an explosion-proof safety chamber is a pin, called below, for simple convenience, base pin, to distinguish it from the pins of the plug, this pin base protrudes axially on the bottom of the explosion-proof safety chamber which it equips, and the corresponding contact piston has, at the rear, on the side of said bottom, a cell, by which it is intended to cooperate with said pin of base.

As a variant, this contact member is a stud, this stud protrudes axially from the bottom of the explosion-proof safety chamber which it equips, and the corresponding contact piston is a telescopic piston, that is to say a piston formed of at least two piston elements mounted axially movable with respect to one another against elastic spacing means urging them in axially opposite directions, that of these piston elements which is at the front having the associated cell while the one at the rear is intended to cooperate with said pad, by simple pressing against it.

In all cases, the base according to the invention advantageously remains simple and its size is reduced.

In addition, no particular device such as bayonet mounting or key being required, the pins of the plug can be simple pins, established according to a usual layout, and therefore respecting the interchangeability ratings provided for by the official standards in matter.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended schematic drawings in which:

• la figure 2 est une vue partielle en élévation de ce socle, suivant la flèche Il de la figure 1;
• la figure 3 reprend, à échelle supérieure, le détail de la figure 1 repéré par un encart III sur celle-ci;

Figure 1 is a sectional view of a base for a safety socket according to the invention, along the broken line II of Figure 2;

• Figure 2 is a partial elevational view of this base, along the arrow II of Figure 1;
• Figure 3 shows, on a larger scale, the detail of Figure 1 identified by an insert III thereon;

Figure 4 itself takes up on a larger scale the detail of Figure 3 identified by an insert IV thereon;

Figures 5A, 5B, 5C are on a different scale, partial views similar to that of Figure 1 and illustrate various phases of implementation of the base for safety socket outlet according to the invention;

Figure 6 is, on a scale also different, a partial sectional view of an alternative embodiment of this base for safety outlet, along line VI-VI of Figure 7;

Figure 7 is a cross-sectional view along the line VII-VII of Figure 6;

Figures 8, 9 are detailed views similar to that of Figure 3 and each relate respectively to other embodiments of the base for safety outlet according to the invention.

As illustrated by these figures, the safety socket outlet concerned by the present invention usually comprises a female part 10, or base, and a male part 11, or plug.

In the embodiments shown, the base 10 is carried by a housing 12, called "increased safety", by means of which it can be attached to any support.

Since such a housing 12 is well known in itself, and not part of the present invention, it will not be described in detail here.

It will suffice to indicate that, for the implantation of the base 10, it comprises a well 13, that the base 10 is suitably secured to the bottom 14 of this well 13 by resting on this bottom 14 by a shoulder 15 or a flange 15 'that it has transversely for this purpose, that it crosses the central opening 16 of said bottom 14, that it provides between itself and the side wall of said well 13 an annular volume suitable for the insertion of the skirt 18 of the sheet 11, that at the bottom of said well 13 is disposed a seal 19, for support of the edge of said skirt 18 of sheet 11, and that, on the outer wall of well 13, is articulated a clean cover 20 to ensure its watertight closure in the absence of such a plug 11.

In practice, in the embodiments shown, and in a manner known per se, the cover 20 which is urged in the direction of its closed position 20 by a spring 71, is intended to be applied to the outlet of the well 13, and , for the desired seal, it bears annularly, in a groove 77, a seal 79.

Furthermore, in the embodiments shown, and in a manner also known per se, the side wall of the well 13 forms. locally, a longitudinal groove 21 suitable for constitute a key, the skirt 18 of the plug 11 locally comprising, in correspondence, over at least part of its height from its edge, a bead 22 complementary to such a groove.

Sheet 11, which has only been partially shown in the figures, and, in practice, only in FIGS. 5A, 5B, 5C, is also not part of the present invention, and, well known to man of art, it will not be described in detail here.

It will suffice to specify that, externally, its skirt 18 has transversely projecting a flange 23, for bearing on the edge of the well 13 of the housing 12, and that, internally, it comprises, projecting from a base not visible in the figures, in addition to a possible earth pin 25, as shown, at least two phase or neutral pins 26.

In practice, in the embodiment shown, and for simplification of the figures, only two pins 26 have been provided; these are phase pins, the current outlet being assumed to interest a single-phase network.

In a manner known per se, the base 10 forms a body of insulating material, and, for cooperation with the pins of the plug 11, it comprises, in addition to a possible earth cell 28, as shown, at least two phase cells or neutral 29.

As indicated above, only two cells 29 have been provided, and these are phase cells.

According to the invention, the base 10 comprises at least as many separate chambers 30 as there are phase or neutral cells 29, said phase or neutral cells 29 being each individually arranged in said chambers 30, and it these are explosion-proof security chambers.

In practice, in the embodiment shown, the number of explosion-proof safety chambers 30 used is equal to that of the phase or neutral cells 29, no explosion-proof safety chamber being provided for the cell of earth 28.

Indeed, such an earth cell 28 does not normally require by itself the implementation of such an explosion-proof safety chamber.

But, of course, there would be no escape from the present invention if the procedure were for this earth cell 28 as for the phase or neutral cells 29.

On the internal or rear side of the base 10, each of the explosion-proof safety chambers 30 is individually closed, in the embodiments more particularly shown in FIGS. 1 to 7, and the same is true for that shown in FIG. 9 , by a plug of insulating material 63, which forms the bottom 32 of such an explosion-proof safety chamber 30.

The axial interlocking length L of such a plug 63 in such an explosion-proof safety chamber 30, which corresponds to a line of flight, is made sufficient to meet the requirements to be met in this area.

In the embodiments shown in FIGS. 1 to 7, and 9, the set of plugs 63 thus present are jointly capped, externally, by a cover 64, which is common to them, and which, externally, itself comprises as much cells 66 that there are phase or neutral cells 29, with, in each of these, a contact piece 67.

In the corresponding socket 66, it is associated with such a contact piece 67, for its electrical connection to any electrical conductor not shown, a stirrup 68 suitable for clamping this electrical conductor against said contact piece 67 under the stress of 'a screw 69.

On the external side, or front, the base 10 comprises, for each explosion-proof safety chamber 30, a collar 34, which extends transversely in such an explosion-proof safety chamber 30, and the opening 35 of which defines the outlet to the outside of it.

Of course, the diameter D of this opening 35 corresponds to that of the pins 26 of the plug 11.

Of course, also, the axial length L ′ of the collar 34, which also defines a line of flight, is at least equal to the axial length L specified above, for compliance with the standards in the matter, and is for example equal to this one.

It is in fact thanks to such provisions that a security chamber 30 constitutes an explosion-proof security chamber.

In an explosion-proof safety chamber 30 thus formed, there are arranged, according to the invention, on the one hand, on the bottom 32 of this explosion-proof safety chamber 30, a contact member, and, on the other hand, mounted axially movable therein, a contact piston 40, which divides said explosion-proof safety chamber 30 into two portions, and which, at the front, on the side of the outlet 35 thereof, presents the phase cell or of associated neutral 29.

In the embodiments more particularly shown in FIGS. 1 to 8, the contact member present on the bottom 32 of an explosion-proof safety chamber 30 is a pin 37, referred to below for convenience as a base pin.

In practice, this base pin 37, which is metallic, projects axially from the bottom 32 of the explosion-proof safety chamber 30 which it equips, and, passing through the corresponding plug 63, by means of an axial bore 43 of the latter, the axial length L ″, for the same reasons as above, is preferably at least equal to the axial length L specified above, it is in one piece with the associated contact piece 67.

At the same time, for cooperation with the corresponding base pin 37, the piston contact 40 has, at the rear, on the bottom side 32 of the explosion-proof safety chamber 30 in which it is slidably mounted, in the embodiments shown in FIGS. 1 to 8, a cell 47, or rear cell, by which it is adapted to cooperate with said base pin 37.

In practice, such a contact piston 40, which is metallic, therefore thus presents, in the embodiments shown in FIGS. 7 to 8, each arranged respectively back to back on either side of a common central base 48 by which it is slidably engaged in the explosion-proof safety chamber 30 which it equips, on the one hand, in the direction of the outlet 35 thereof, the corresponding phase or neutral cell 29, and, on the other hand part, in the direction of its bottom 32, the cell 47.

In addition, in these embodiments, at least one of the cells 29, 47 of each of the contact pistons 40 has internally, at a distance from its bottom, a transverse shoulder 70 capable of limiting its engagement on the plug pin or corresponding base; preferably, and as shown, this is the case for both of them.

In practice, and in a manner known per se, each of these cells 29, 47 is circularly fragmented by slots 50, so as to be able to have a certain elasticity radially, and thus elastically tighten the corresponding pin 26, 37 when it is engaged with it.

Preferably, for such tightening, each of the cells 29, 47 is elastically subjected to a radial prestress with respect to the corresponding pin 26, 37.

For example, and in a manner known per se, this is due to the effects of a hoop ring 57, forming a spring, which annularly surrounds such a cell 29, 47, outside of the latter.

In practice, in the embodiment shown, the cells 29, 47 have, overall, the same axial length, and the same constitution.

In practice, too, the stroke of the contact piston 40 in the explosion-proof safety chamber 38 which it equips is made sufficient so that, when it is at the end of the forward stroke, on the outlet side 35 of said explosion-proof safety chamber 30, as shown in Figure 3, it has no contact with the base pin 37 forming the associated contact member.

Preferably, it is then separated from the latter by a distance D ′, which, corresponding to a distance in the air after drawing out, is made sufficient to meet the standards in the matter.

Also preferably, and as shown, with such a contact piston are associated, in the embodiments shown in FIGS. 1 to 8, disengageable snap-on means capable of strengthening its position when it is at the end of forward race.

In the embodiment shown, these disengageable snap-fastening means comprise, on the one hand, an elastic ring 53, for example an elastic ring opened by a slot, which is engaged in a groove 54 annularly provided for this purpose at the periphery external of the contact piston 40, in the central zone of the central base 48 thereof, and, on the other hand, a groove 55, which, in a complementary manner, is also annularly provided for this purpose on the internal wall of the corresponding explosion-proof safety chamber 30, for engagement of said elastic ring 53

Preferably, the distance 1 axially separating each of the sides of the groove 54 of the contact piston 40 from the corresponding free surface of the central base 48 thereof is at least equal to half of the axial length L specified below. above.

Given these latching means, and as it is better visible in FIG. 3, for its front end-of-travel position, the contact piston 40 is not axially in abutment against the collar 34 defining the outlet 35 of the explosion-proof safety chamber 38 concerned, but on the contrary is slightly away from the internal surface 39 thereof.

In the embodiments shown in FIGS. 1 to 7, and 9, each of the contact pistons 40 is subjected to elastic return means which urge it permanently towards its front end position, that is to say that is to say towards the outlet 35 of the explosion-proof safety chamber 30 in which it is movably mounted.

In practice, in these embodiments, these elastic return means are constituted by a metal spring 60, of the coil spring type, and said spring 60 acts by means of a spacer made of insulating material 61 on the contact piston. 40 with which it is thus associated.

In the embodiments concerned, such a spacer 61 forms a bushing which, bearing on the central base 48 of the contact piston 40, extends annularly around the rear cell 47 thereof, extending, in practice, and as shown, beyond the free edge of this rear cell 47.

Jointly, the spring 60, which extends annularly around the corresponding base pin 37, itself bears on the plug 63 forming the bottom 32 of the explosion-proof safety chamber 38 concerned.

Finally, in the embodiments shown, are articulated on the housing 12 of the base 10, in addition to the cover 20, a latch 73. which is capable of ensuring by a notch 75 the ¹ holding in the closed position of the cover 20, and which is itself biased towards the corresponding position by a spring 76.

According to the invention, the latch 73 has, beyond the first, a second notch 80, by which it is adapted, as will appear below, to retain, at least temporarily, in the intermediate position, the plug 11 , when extracting this one.

In practice, and as shown, this second notch 80 is formed on an extension 82 of the latch 73, and it is preceded by an oblique engagement chamfer 83.

In the embodiments shown, the axes of articulation of the cover 20 and the log 73 are arranged in diametrically opposite positions relative to each other relative to the well 13, and, for cooperation with the notch 75 of the latch 73, the cover 20 has, radially projecting at its periphery, a spoiler 85.

Similarly, for cooperation with the notch 80 of the latch 73, the skirt 18 of the plug 11 has a spoiler 87 radially projecting from the flange 23 which it usually comprises for its support on the outlet of the well 13 of the base 10.

In the standby position, the cover 20 is closed, and the contact pistons 40 are in the front end-of-travel position, with snap-fastening of the elastic ring 53 which it carries in the groove 55 of the explosion-proof safety chamber 30 corresponding, as shown in Figures 1, 3 and 5A.

They are therefore de-energized, and the corresponding base pins 37, which are energized, are inaccessible.

The introduction, or commitment, of sheet 11 is done in two stages.

Initially, the cover 20 is opened by momentary spacing of the latch 73, the plug 11 is presented in line with the well 13, FIG. 5A, and, after temporary retraction of the latch 73 by action on the engagement chamfer 83 of that here, first by the edge of its skirt 18, FIG. 5A, then by the flange 23 thereof, it is engaged in this well 13, with penetration of its pins 26 into the phase or neutral cells 29 contact pistons 40, FIG. 5B, until they stop against the transverse shoulder 70 thereof, and penetration of its earth pin 25 into the earth socket 28.

On the one hand, by their snap-fastening in the front end-of-travel position by the elastic ring 53 which it carries, and, on the other hand, by the stress of the spring 60 which is associated with them, the pistons of contact 40 remain, momentarily, in their front end-of-travel position, despite the driving force of which they are however the object, by friction, when the pins 26 of the plug 11 penetrate.

In fact, by construction, the axial force that opposes the engagement of a plug pin 26 due to its radial prestressing, the front cell 29 of a contact piston 40, is less than the sum of the axial force required to disengage the latching means that constitutes the elastic ring 53 which such a contact piston carries, on the one hand, and the axial force necessary to overcome the effects of the associated spring 60, somewhere else; it is therefore this front cell 29 which elastically yields the first during such engagement.

Thus the connection of the pins 26 of the plug 11 with the contact pistons 40 according to the invention is advantageously done even when the latter are de-energized.

In a second step, the engagement of the plug 11 in the well 13 of the base 10 being continued, the pins 26 of the latter, bearing on the transverse shoulder 70 _′ corresponding to the pistons of contact 40, cause its drive in the direction of the base pins 37, the elastic ring 53 which they carry yielding elastically and passing in retracted configuration in contact with the internal wall of the corresponding explosion-proof safety chamber 30, and they thus constrain these contact pistons 40 to s 'engage by their rear cell 47 on said pins 26, Figure 5C.

Jointly, the springs 60 associated with the contact pistons 40 compress.

The contact pistons 40 thus being engaged on the one hand with the pins 26 of the plug 17 and on the other hand with the base pins 37, they establish an electrical contact from these pins 26 to these pins 37, as sought.

In the usual way, the plug 11 is then locked in the engagement position, by a spoiler 90 which it has for this purpose laterally projecting and with which a spoiler 91 of the cover 20 cooperates in retention.

The extraction, or withdrawal, of sheet 11 is also done in two stages.

Initially, a pulling action being exerted on the plug 11, the withdrawal of the latter is limited by abutment of the spoiler 87 of the flange 23 of its skirt 18 against the notch 80 of the latch 73, such as shown in Figure 5B.

But, due, on the one hand, to the driving force of which they are the object on the part of the soft-cover 26 of the sheet 11, and, on the other hand, to the axial restoring force of which they are also the object on the part of the springs 60 which are associated with them, the contact pistons 40 follow the plug 11 in its withdrawal movement.

In fact, by construction, the axial return force of which such a spring 60 is capable, according to the invention, is preferably greater than the axial force due to friction, on the internal wall of the explosion-proof safety chamber 30 concerned. , of the elastic ring 53 carried by each of the contact pistons 40.

In return, the radial prestressing which is the object of the cells 29, 47 of such a contact piston to the fact of the hooping ring 51 which surrounds them can advantageously be the same for both of these cells 29, 47, and therefore the corresponding hooping rings 51 are identical.

In practice, it is made so that for the intermediate position of the plug 11 due to the notch 80 of the loguet 73, the contact pistons 40 are themselves in the front end position, the elastic ring 53 which they bear again engaging with the groove 55 of the corresponding explosion-proof safety chamber 30, resuming, by elasticity, its configuration initial deployed.

For this intermediate position of the plug 11, leaving the term of the first time of the extraction of this, there is therefore a withdrawal of the contact pistons 40 relative to the base pins 37, and, these contact pistons 40 thus being de-energized, the same applies to the pins 26 of the plug 11 with which they are still engaged.

It is thus advantageously possible to leave permanently, if desired, the plug 11 on the base 10, while ensuring the drawout thereof, which very simply solves the permanent problem of the deactivation of this plug 11 in good backup conditions, especially when this decommissioning should only be temporary.

In a second step, if desired, the extraction of the plug 11 can be continued, by retracting the latch 73.

Its pins 26 then separate from the contact pistons 40, while the latter remain in the front end position which was already theirs.

However, according to the invention, the corresponding disconnection advantageously takes place even though these contact pistons 40 are already de-energized.

As a corollary, under the stress of its spring 71, the flap 20 closes, and, its spoiler 85 engaging with the notch 75 of the latch 73, it is held in the closed position by the latter.

Anyway, when the withdrawal of the plug 11 must be total, the latch 73 according to the invention advantageously requires a split in two stages of this withdrawal, on the one hand, to move said plug 11 from its position to its intermediate position, for which, as stated above, it is already removed, and, on the other hand, to then withdraw it completely.

Such a split in two stages of this withdrawal advantageously makes it possible to alleviate the possible consequences of a too rapid withdrawal, which, in particular when the currents to be cut are very inductive, could lead the plug 11 to be inadvertently and dangerously followed outside. by the arc arising from its removal.

In all cases, given the return spring 60 associated therewith and the elastic ring 53 confirming their front end-of-travel position, the contact pistons 40 advantageously remain permanently de-energized in the absence of the plug. 17.

Consequently, the engagement of the plug pins 26 in these contact pistons 40 is done with complete certainty while the latter are de-energized, without contact with the associated base pins 37.

In addition, no false maneuver is possible, if, for example, during an engagement of the plug 11 on the base 10, there is a premature withdrawal of this plug 11, before this engagement has reached its normal term.

In this case, by the pins 26 of the plug 11 with which they are necessarily engaged, the contact pistons 40 are necessarily brought back to the front end-of-travel position, without the risk of being abandoned in an intermediate position, for which they could be in contact with the corresponding base pins 37, and therefore be energized.

Furthermore, and as will be understood, the internal shoulder 70 which, in the embodiments shown in Figures 1 to 7, and 9, has each of the cells 29, 47 of the contact pistons 40 advantageously allows to minimize the corresponding engagement strokes on the pins 26, 37, while leaving said cells 29, 47 all the desirable length so that they have good elasticity.

As illustrated in Figures 6, 7, a keying device can be provided, to avoid the establishment of a plug 11 which does not comply with the desired safety standards.

In such a case, there is provided, radially projecting from the collar 34 of the earth socket 28, a rib 92, and, in addition, there is a groove on the corresponding earth pin 25 of the plug 11 .

In the variant embodiment illustrated in FIG. 8, no spring biases the contact pistons 40 in the direction of their front end-of-travel position.

However, by construction, by an appropriate choice of the characteristics of the various constituents in question, it is ensured that, with respect to the corresponding pins 26, 37, the radial prestressing which is the object of the front cell 29 d such a contact piston 40 is greater than that of its rear cell 47.

Jointly, it is also made so that the axial force due to the tightening of a plug pin 26 by such a front socket 29 of the contact piston 40 under the effects of the radial preload thereof is greater than the sum of the axial force due to the tightening of the corresponding base pin 37 by the cell 47 thereof under the effects of the radial prestressing of this rear cell 47, on the one hand, and of the axial force due to the friction, on the internal wall of the explosion-proof safety chamber 30, of the elastic ring 53 carried by said contact piston 40, on the other hand.

As a result, when, a plug 11 being engaged with the base 10, this plug 11 is removed, there is first of all, as previously, firstly, a drive, by the pins 26 of the latter, from each of the contact pistons 40 that said base 10 comprises, then, in a second step, a clearance of said pins 26 from these contact pistons 40.

In the embodiment shown, each of the contact pistons 40 is then abutment against the internal surface 39 of the collar 34 forming the outlet 35 of the explosion-proof safety chamber 30 corresponding.

But, of course, it can still be at a slight distance from it, as previously, its front end-of-travel position then being defined by the elastic ring 53 which it wears when the latter engages the groove 55 of said explosion-proof safety chamber 30.

Conversely, when a plug 11 is engaged on this base 10, there is, first of all, firstly, and as previously, an engagement of the pins 26 of this plug 11 in the front cells 29 of the contact pistons 40, without training thereof.

In fact, it is ensured, in this case, that the axial force that opposes the engagement of a plug pin 26, due to its radial prestressing, the front socket 29 of such a piston contact 40 is less than the axial force required to disengage the disengageable locking means associated with these contact pistons 40.

It is therefore this front cell 29 which, as before, still yields the first.

In a second step, when, the pins 26 of the plug 11 having arrived, in the embodiment shown, at the bottom of the front cells 29 of the contact pistons 40, the engagement of this plug 11 on the base 10 is continued, the axial force required to disengage the disengageable locking means associated with these contact pistons 40 is in turn overcome, and these contact pistons 40 are therefore driven by the plug 11.

During this training, the contact pistons 40 in turn engage, by their rear cell 47, on the base pins 37.

Furthermore, in this embodiment, the corresponding rear end-of-travel position of the contact pistons 40 is defined by the bottom 32 of the explosion-proof safety chamber 30 in which they are mounted to be movable.

In practice, in this embodiment, the plug 63 thereof forms an integral part with the associated cover 64, this cover 64 directly presenting the bore 43 necessary for passing through an extension 42 of the associated base pin 37, around an annular end piece 33 suitable for its local fitting into the explosion-proof safety chamber 30 concerned, and said extension 42 of said base pin 37 is tubular, for crimping onto the conductive core of an electrical conductor.

In the embodiment shown in FIG. 9, the contact member present on the bottom 32 of each of the explosion-proof safety chambers 30 is a stud 97, which, like the previous pin 37, protrudes from said bottom 32, and the contact piston 40 mounted mobile according to the invention in such an explosion-proof safety chamber 30 is a telescopic piston, that is to say a piston formed by at least two piston elements 98, 99 mounted axially mobile l ' one over the other.

In practice, in this embodiment, only two piston elements 98, 99 are thus provided, and elastic spacing means, in this case a spring 100, urge them in axially opposite directions with respect to the 'other.

The piston element 98, which is that disposed at the front, on the side of the outlet 35 of the corresponding explosion-proof safety chamber 30, comprises the phase or neutral cell 29 associated, with, as before, slots 50 and a hooping ring 51, while the piston element 99, mistletoe is therefore that arranged at the rear, on the side opposite to said outlet 35, is intended to cooperate with the stud 97, by simple pressing against it.

In the embodiment shown, the piston element 98 forms at the rear, a cell 102, in which the piston element 99 is engaged, and the outlet of which is bordered by a transverse return 103 in the direction of its axis. .

The piston element 99 itself forms a cell 104, by which it is engaged in that 102 of the piston element 98, and the side wall of which is circularly fragmented by slots 105, with, externally, projecting from the end of the latter, in the direction opposite to its axis, a transverse return 106 suitable for coming into engagement with that 103 of said piston element 98, for its retention with respect to the latter.

The spring 100 is housed in the volume defined by these two cells 102, 104, bearing on the bottom of each of these.

Externally, for cooperation with the stud 97, the piston element 99 carries a contact grain 108, and, similarly, for cooperation with it, said stud 97 carries a contact grain 109.

The contact grains 108, 109 are preferably made of a metal or alloy chosen for its good conductivity.

In the embodiment shown, the stud 97 is quite similar, in terms of its length, to the previous pin 37.

However, as a variant, it could have only a limited length, just sufficient for the contact grain 109 which it carries to actually protrude from the bottom 32 of the explosion-proof safety chamber 30 concerned.

For the rest, the embodiment shown in Figure 9 is of the same type as that shown in Figures 1 to 5, with. in particular, individual plug 63, spring 60 and spacer 61.

Anyway, the simple support contact developed between contact piston 40 and pad 97 in this embodiment makes it possible to avoid any seizure between these members when current and / or voltage are high, which is favorable the breaking capacity of the assembly.

Of course, the present invention is not limited to the embodiments described and shown, but encompasses any variant embodiment and / or combination of their various elements.

In particular, in the case where the contact pistons each having two cells, Differentiated radial preloads are sought for these cells, the base pins can be made slightly smaller in diameter than the plug pins.

Such an arrangement advantageously also makes it possible to have symmetrical contact pistons, which simplifies manufacture and assembly.

In addition, the well in which is placed the barrel comprising the phase or neutral cells of the base can form a part which, distinct from the housing of this base, is suitably attached thereto, for example by screws, by enclosing a flange with sides provided for this purpose radially projecting from this barrel, which makes it possible, in particular, to give this barrel a given angular orientation around its axis, as a function of the envisaged operating voltages, while ensuring axial retention suitable, without other means of attachment.

Furthermore, the field of application of the invention is not limited to the case where, in the case of a single-phase installation, two phase cells are used.

On the contrary, it extends for example as well to three-phase installations, for which three phase cells are used, with, optionally, a neutral cell, in addition to a possible earth cell.

Claims (23)

1. A socket for a safety current connection, in particular for an explosive atmosphere, of the type comprising, for co-operation with the pins (26) of a current connection plug (11), besides an optional earth socket member (28), at least one phase or neutral socket member (29) disposed in a chamber (30), with, in said chamber, on the one hand a contact member (37, 97) on the bottom (32) of the chamber, and on the other hand, and mounted axially movably, a contact piston (40) which divides said chamber into two portions and which at the front, at the side of the opening (35) of the chamber, has the associated phase or neutral socket member (29), characterised in that the travel length of the contact piston (40) in the chamber (30) is sufficient that, when it is at the forward limit of its travel movement, towards the opening (35) of said chamber, it is without any contact with the associated contact member (37, 97).

2. A socket according to claim 1 characterised in that the chamber (30) in which a contact piston (40) is movably mounted is an anti-spark safety chamber.

3. A socket according to claim 1 characterised in that there are at least as many separate chambers (30) as there are phase or neutral socket members (29), with, in each thereof, a contact piston (40) having the corresponding phase or neutral socket member (29).

4. A socket according to any one of claims 1 to 3 characterised in that the contact member (37, 97) is a pin (37), referred to hereinafter as the socket pin, which projects axially from the bottom (32) of the chamber (30), and at the rear, towards said bottom (32), the contact piston (40) has a socket member (47) by means of which it is adapted to co-operate with said socket pin (37).

5. A socket according to any one of claims 1 to 3 characterised in that the contact member (37, 97) is a stud (97) which projects axially from the bottom (32) of the chamber (30) and the contact piston (40) is a telescopic piston, that is to say a piston formed by at least two piston elements (98, 99) which are mounted axially movably with respect to each other against resilient spreadling means (100) urging them in axially opposite directions, that one (98) of said piston elements which is at the front having the associated phase or neutral socket member (29) while that (99) which is at the rear is intended to co-operate with said stud (97), by simply bearing thereagainst.

6. A socket according to either one of claims 4 and 5 characterised in that in a chamber (30), the contact piston (40) is subjected to resilient return means (60) which urge it constantly forwardly.

7. A socket according to claim 6 characterised in that the resilient return means (60) associated with a contact piston (40) being formed by a metal spring of the coil spring type, which bears against the bottom (32) of the chamber (30), said spring acts against said contact piston (40) by way of a spacer member (61) of insulating material.

8. A socket according to claims 4 and 7 in combination characterised in that the spacer member (61) interposed between the contact piston (40) and the spring forming its resilient return means (60) forms a sleeve which, bearing against its central flange (48), extends in an annular configuration around its rearward socket member (47).

9. A socket according to claim 8 characterised in that said sleeve extends beyond the rearward socket member (47) of the contact piston (40)

10. A socket according to any one of claims 1 to 9 characterised in that the phase or neutral socket member (29) provided on a contact piston (40) is internally provided, at a spacing from its bottom, with a transverse shoulder (70) for limiting engagement thereof on to the corresponding pin (26) of a plug (11).

11. A socket according to claim 4 characterised in that the rearward socket member (47) provided on a contact piston (40) is provided internally, at a spacing from its bottom, with a transverse shoulder (70) for limiting the engagement thereof on to the corresponding socket pin (37).

12. A socket according to any one of claims 1 to 11 characterised in that associated with a contact piston (40) are disengageable latching means for establishing the position thereof when it is at the forward limit (39) of its travel movement.

13. A socket according to claim 12 characterised in that said disengageable latching means comprise a resilient ring (53) engaged into a groove (54) annularly provided for that purpose at the outside periphery of the contact piston (40) in a central zone thereof and a groove (55) annularly provided in a complementary fashion in the inside wall of the chamber (30) for engagement of said resilient ring (53).

14. A socket according to claim 4 characterised in that each of the socket members (29, 47) of the contact piston being resiliently subjected to a radial prestress with respect to the corresponding pin for example under the effects of a hooping ring (51) forming a spring, the radial prestress of the front socket member (29) is higher than that of the rearward socket member (47).

15. A socket according to claims 13 and 14 in combination characterised in that the axial force due to the clamping of a plug pin (26) by the front socket member (29) of the contact piston (40) under the effects of the radial prestress thereof is higher than the sum of the axial force due to the clamping of the socket pin (37) by the rearward socket member (47) of the contact piston (40) under the effects of the radial prestress thereof, on the one hand, and the axial force due to friction against the inside wall of the chamber (30) of the resilient ring (53) carried by said contact piston (40), on the other hand.

16. A socket according to claims 12 and 14 in combination characterised in that the axial force which is opposed to engagement of a plug pin (26), by virtue of its radial prestress, by the front socket member (29) of the contact piston (40), is lower than the axial force necessary for disengagement of the disengageable latching means associated with said contact piston (40).

17. A socket according to claims 6, 12 and 14 in combination characterised in that the axial force which is opposed to engagement of a plug pin (26), by virtue of the radial prestress thereof, by the front socket member (29) of the contact piston (40), is lower than the sum of the axial force necessary for disengagement of the latching means associated with said contact piston (40), on the one hand, and the axial force necessary to overcome the effects of the resilient return means (60) which are also associated therewith, on the other hand.

18. A socket according to claims 6 and 12 in combination characterised in that the axial return force which the resilient return means (60) asscciated with a contact piston (40) are capable of producing is greater than the axial force due to friction against the inside wall of the chamber (30) in question, of the resilient ring (53) that it carries.

19. A socket according to claim 4 characterised in that the radial clamping prestress to which the front and rearward socket members (29 and 47 respectively) of a contact piston (40) are subjected are the same for each of said socket members.

20. A socket according to any one of claims 1 to 19 and to the casing of which are pivotally connected on the one hand a cover (20) for closure thereof and on the other hand a latch member (73) which by means of a catch (75) is capable of ensuring that said cover (20) is held in the closure position characterised in that on the other side of the first catch (75) said latch member (73) has a second catch (80) by way of which it is adapted at least temporarily to retain the associated plug (11) in an intermediate position, upon extraction of said plug.

21. A socket for a safety current connection according to claim 20 characterised in that said second catch (80) of the latch member (73) is preceded by an inclined engagement bevel (83)

22. A socket according to any one of claims 1 to 21 characterised in that it is carried ty a casing (12) of "enhanced safety' type.

23. A socket according to any one of claims 1 to 22 characterised in that the chamber (30) in which a contact piston (40) is movably mounted being forme directly in the socket, it is fixed with respect thereto.

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