Technical field
[0001] The present invention relates to industrial safety and has in particular for object
a key-controlled safety switch assembly, particularly adapted for use in strongly
dirty and polluting environment.
Background art
[0002] The switches of the described type are normally employed to block cabinet doors or
protection barriers for machines and industrial plants with dangerous moving parts,
like saws, rotors, tools or blades, in which the access time to the area interested
by such parts is shorter than the stopping time of the machine or plant.
[0003] Such switches are essentially made of two distinct elements, namely a box-like case
containing a series of electric contacts connected with the power supply circuit of
the machine, for example with a control coil or relais, and a key-like element insertable
in one or more slots of the case to commute the above-mentioned electric contacts.
Preferably, the box-like case is anchored to the frame of the machine or plant, and
the key-like element is fixed to the door or moving barrier in a position facing a
slot of the box-like case.
[0004] For security reasons, inside the case there are provided blocking parts acting on
the key-like element to block it in its inserted position inside the case until the
dangerous moving parts are completely stopped. To operate the blocking parts there
is provided a special sensor which senses the stopping of the dangerous parts or a
time switch which sends a signal after a time longer the time necessary for stopping
said parts.
[0005] When an operator wants to open the door or barrier, he must at first press a button
placed on the electric control cabinet of the machine, so that the dangerous part
of the machine begins to decelerate progressively. When the sensor detects the condition
of "dangerous part stopped", it will automatically send an electric signal to the
blocking part, thus unlocking the key and allowing the opening of the door or barrier.
[0006] Examples of key-controlled safety switches the type over described are given in the
United States patent No. 4, 904, 829, No. 5, 584, 378, No. 5777284 in the European
applications No. 0 553 885, No. 0 817 227, No. 0 814 490, in the international applications
WO No. 95/06323, 95/18457, 96/33504 and in the German applications No. 3309372 and
3710079.
[0007] A drawback of these known switches is related to the operative environment. In fact,
if they are applied to machines and installations working in particular dirty and
polluting environments, like for example cement production plants, land movement machines,
concrete mixing installations, tile production installations, machining equipment
of stone materials, they are easily subject to damage and malfunction. In fact, the
powder material dispersed in the environment can deposit on the actuating element
or in the box-like case, thus creating on the same layers of adherent material of
great consistency. Progressively, the thickness of such layers can increase and even
reach some millimetres, and can involve the delicate sensing mechanisms of the keys
provoking in short time their seizure and putting them out of use.
[0008] In order to solve this problem a magnetic type recognition device has been provided
which is described in the United States patent n. 5254879, essentially made of two
components protected by respective cases, on one side a simple permanent magnet with
functions of magnetic field generator, on the other an electric switch enclosed in
an tubing (reed) which shuts when influenced by the field produced by the permanent
magnet. Besides, to avoid altering operation of the switch approaching to the tubing
a second magnet similar to the first one, a personalized decoding system of the analogic
(radio waves, radar, etc.) or digital type (EPROM) has been associated to the magnetic
recognition device.
[0009] In an attempt to use the traditional key-controlled switches with mechanical recognition
in very dirty and polluting environments, German patent No. 4209086 discloses a lip-gasket
of rubber or similar material applied at the edge of the input slot of the actuating
key-like element, so as to limit dust and dirt penetration.
[0010] From the British patent No. 2052158 a key-controlled switch is known with a key-like
actuating element provided with a permanent magnet and a tapered end portion. The
permanent magnet has the function of moving a leaf member of insulating material interposed
between two electric contacts contained in the case, which are subsequently closed
by the tapered extremity of the actuating element.
[0011] From the European patent application No. 0 837 485, there is known a key-controlled
safety switch having all the characteristics belonging to the state of the art and
indicated in the preamble of claim 1, and further having a recognition or decoding
device of the key-like element which is both electronic and mechanical, similar to
that of some anti theft systems for motor vehicles. In a preferred embodiment, the
electronic recognition device is essentially constituted of a series of Hall effect
sensors placed on a wall of the insertion slot and facing a series of correspondent
permanent magnets fixed on the key-like element. The tension detected by the Hall-effect
sensors with predetermined and characteristic values of every key.
[0012] This switch has the inconvenience of presenting a great complexity and a comparatively
high cost because of the presence of a key recognition system which is both mechanical
and electronic. Additionally, the mechanical recognition system constitutes a drawback
since it is subject to the risks of stratification of dirt and dust and to consequent
seizures and/or break-downs.
[0013] Furthermore, it is well known, for instance from US-A-5239202, that reed tubings
and contacts may be employed as magnetically controlled switches.
[0014] US-A-5541562 describes a key-controlled safety switch having all the characteristics
indicated in the preamble of claim 1. Moreover, this switch comprises a case with
only two slots placed at two opposite side thereof. The case is provided of three
proximity digital sensors all placed between one side of the case and a locking member.
The actuating element has two holes placed in two opposed extremity portions of the
actuating element for receiving the locking member.
[0015] A main drawback of this known switch resides in that it has only two slots, thus
reducing the freedom of installation on plants requiring insertion of the actuating
element across all four sides of the case. Moreover, the actuating member must have
two holes in order to allow the insertion of the actuating element through either
slots, thus increasing the overall length of the actuating member.
Presentation of the invention
[0016] A primary aim of the present invention is to eliminate the above drawbacks providing
a key-controlled safety switch assembly which is particularly adapted for use in dirty
and polluted environments, ensuring uninterrupted operation at least for a prolonged
period of time.
[0017] A particular aim is to provide a key-controlled safety switch assembly which can
be easily cleaned so as to ensure its functionality and effectiveness by means of
a periodic maintenance.
[0018] A further particular aim is to provide a key-controlled safety switch assembly with
great structural simplicity so as to be reliable and intrinsically safe.
[0019] An other particular aim is to provide an extremely versatile switch assembly, flexible
and of reduced cost.
[0020] In accordance with one preferred aspect of the invention, there is provided a key-controlled
switch assembly according to claim 1.
[0021] Thanks to this particular configuration, the actuating key-like element can be freely
inserted along different directions in corresponding slots also in dirty and polluting
environments, avoiding seizures and technical malfunctions.
Short description of the drawings
[0022] Further characteristics and advantages of the invention will become apparent from
the detailed description of a preferred but not exclusive embodiment of the key-controlled
switch assembly according to the invention, illustrated by way of non-limitative example
in the accompanying drawings wherein:
the FIG. 1 is a general partially exploded perspective view of a key-controlled switch assembly
according the invention;
the FIG. 2 is a front view of a partial section taken along the axial plane II-II of the assembly
of Fig. 1, in a first operative position;
the FIG. 3 represents a side view of a partial section of the assembly of Fig. 2 taken along
the axial plane III-III;
the FIG. 4 represents a side view of the assembly of Fig. 3 in a first operational phase;
the FIG. 5 represents a lateral sight of the assembly of Fig. 4 in a second operational phase.
Detailed description of a preferred embodiment
[0023] With reference to the cited figures, a key-controlled switch assembly according to
the invention, globally designated with the reference numeral 1, comprises a box-like
case 2, of substantially parallelepiped form with main axis V, and a key-like actuating
element 3.
[0024] The case 2 is preferably anchored to the frame of a machine or installation, with
dangerous moving parts and not shown in the drawings, by means of screws 4. The case
2 has on a lateral wall and in vicinity of one extremity axial portion at least a
through slot 5 for the insertion of the key-like actuating element 3.
[0025] In the illustrated form, on all four sides of the case 2, there is provided a slot
5 to allow the insertion of the key-like actuating element 3 from all sides.
[0026] The element 3 can be in this way fixed to the moving part of a protection or barrier
of the machine or installation, also not represented on the drawings, in position
facing one of the slots 5 of the case 2.
[0027] The case 2 has internally thereof a safety electric circuit, globally designated
with the reference numeral 6, having end connectors 7, 8 connected to a general relais
of the machine or installation to control its starting or stopping on insertion and
on extraction of the actuating element 3 in the slot 5.
[0028] A locking part or electromagnetic bolt 9 is also placed in the case 2, comprising
a substantially cylindrical armature 10 enclosed by an electromagnet coil 11, which
armature extends out of the head of the coil 11 and can be inserted in a hole 12 placed
in the straight portion 12' of the actuating element 3 when the latter is inserted
in the slot 5, firmly locking it and preventing its extraction as long as the dangerous
part of the machine is moving.
[0029] Advantageously, the armature 10 has a prominence 10' projecting from the lower part
of the winding 11 whose function will be explained hereinafter.
[0030] Finally, in the case 2 there is placed a detecting device 13 adapted to detect the
position of said actuating element 3 to allow activation of the electric bolt 9.
[0031] In accordance with the invention, the detecting device 13 is of exclusively electronic
type acting from a distance, and the key-like element 3 is shaped to enter freely
in the slot 5 with a predetermined clearance
s.
[0032] The actuating element 3 has a straight end portion 12 with constant cross section,
of similar form and of dimensions smaller than those of the slot 5, and substantially
smooth lateral surfaces. Thus, on insertion of the portion 12' of the element 3, the
clearance
s will be distributed in substantially uniform manner along the entire periphery C
of the cross section of the portion 12' of the element 3 and there will not be any
mechanic interaction between the two elements of the switch assembly. The clearance
s, equal to some millimetres, will allow an optimal operation also in strongly dirty
and polluting environments as the stratifications on the actuating element will not
cause a seizure for a period sufficient to carry out a scheduled maintenance and an
accurate cleaning of the moving parts.
[0033] In particular, the detecting device 13 is a magnetic proximity switch.
[0034] In particular, the magnetic proximity switch is made of a tubing 13, denominated
commonly reed, that contains electric contacts that are shut if in the vicinity of
a magnetic flux. The tubing 13 is suitable to co-operate with a permanent magnet 14
fixed to the key-like actuating element 3, in an extremity portion of the latter so
as to be close to the tubing 13 adjacent to the insertion slot 5.
[0035] More precisely, a magnetic tubing 13 is placed close to every slot 5 of the body
2 and all tubings are connected in parallel through a first integrated circuit. Thus,
inserting the actuating element 3 in an any of the four slots 5, a signal will be
issued by the recognition device 13.
[0036] Possibly, the detecting device 13, 14 can include a transponder or a radar transmitter/receiver,
not illustrated in the drawings, so as to avoid decoding with the ordinary commerce
means.
[0037] The tubings 13 that constitute the detecting device are connected in parallel to
the safety electric circuit 6, in particular to a first section 15 that comprises
a first pair of electric contacts 16, 17 fixed on a second integrated circuit 15'
perpendicular to the first. By means of a special integrated operator, also enclosed
in the circuit 15', the two contacts 16, 17 can be closed in response to a signal
produced by any of the tubings 13 of the detection device, on insertion of the actuating
element 3 in the correspondent slot 5.
[0038] The safety electric circuit 6 includes additionally a second pair of electric contacts
18, 19 connected to the first pair of electric contacts 16, 17 by a bridge 18' and
placed in a covering 20 made of insulating material. From the covering 20 a button
21 leans out for commuting the state of the contacts 18, 19.
[0039] As can be seen in the Fig. 3, when the electromagnet coil 11 is not excited the armature
10 is blocked in the hole 12 of the actuating element 3, the prominence 10' is at
a distance from the button 21 of the covering and the contacts 18, 19 are normally
closed. On the contrary, when the electromagnet is excited, as shown in the Figure
4, the armature 10 is disengaged from the hole 12 and the prominence 10' compresses
the button 21 and causes the aperture of the contacts 18, 19.
[0040] In use, when the machine or installation is in operation and the barrier or door
is closed, the actuating element 3 is inserted completely in the slot 5 and remains
locked inside it by the bolt 9. On the electric side, all the contacts 16, 17, 18,
19 are closed and the actuating relais of the machine or installation is excited,
as shown in Figure 3.
[0041] When the operator stops the machine or installation and all the dangerous parts are
still, a sensor will send an electric signal to the coil 11 of the bolt 9 which will
open the contacts 18, 19 and will free the actuating key-like element 3 from its engagement
with the armature 10.
[0042] The operator can thus open manually the door or barrier by pulling out the actuating
element 3. As the latter is at a distance of some millimetres from the slot, the magnetic
flux produced by the permanent magnet 14 will reduce its influence on the tubing 13,
consequently opening its electric contacts and then opening also the contacts 16,
17 of the section 15 of the safety circuit.
[0043] From the foregoing description, it is apparent that the key-controlled safety switch
assembly according the invention reaches fully the objects set above and in particular
its structural simplicity, reliability, flexibility and contained cost are underlined.
[0044] The key-controlled safety switch assembly according the invention is subject to numerous
modifications and variations, all of which are within the scope of the accompanying
claims. All the details may furthermore be substituted with other equivalents without
departing from the scope of the invention.
1. Key-controlled safety switch assembly, comprising a box-like case (2) anchorable to
a fixed part of a protection or barrier of a machine or installation and provided
with one or more slots (5), an actuating element (3) anchorable to a moving part of
said protection and having a straight portion (12') insertable in any of said slots
(5), said case (2) having at least four sides and containing internally thereof a
safety electric circuit (6) for selectively closing/opening a general relais or a
safety switch of said machine or installation on insertion/extraction of said actuating
element (3), a locking member (10) adapted to be inserted in a hole (12) placed in
said straight portion (12') to selectively lock said actuating element (3) in the
inserted position in a slot (5) as long as the dangerous parts of the machine or installation
are moving, a detecting device (13) which is exclusively of electronic type acting
from distance and is adapted to detect the position of said actuating element (3)
to allow closing of said safety electric circuit (6), said detecting device (13) comprising
a permanent magnet (14) fixed to said actuating element (3), said detecting device
(13) further comprising at least one recognition device (13) adapted to co-operate
with said permanent magnet (14), characterized in that each recognition device (13) is associated with a respective side of said case (2),
slots (5) being provided on the at least all four sides of the case (2), each slot
(5) on one different side of the case (2), said at least one recognition device (13)
being placed in proximity of each slot (5), each recognition device (13) being placed
between the respective side to which it is associated and said locking member (9)
in order to co-operate with said permanent magnet (14) fixed to said actuating element
(3) inserted in any slot (5), said locking member (10) being placed centrally in the
case (2), said actuating element (3) being shaped to freely enter in said slot (5)
with a predetermined clearance (s).
2. Key-controlled safety switch assembly according to claim 1, characterised in that said straight portion (12') of the actuating element (3) has a substantially constant
cross section and smooth lateral surfaces so as to avoid any mechanical interference
with said slot (5).
3. Key-controlled safety switch assembly according to claim 1, characterised in that each recognition device (13) is a tubing with magnetic contacts.
4. Key-controlled safety switch assembly according to claim 3, characterised in that all said tubings (13) are connected in parallel to said safety circuit (6).
5. Key-controlled safety switch assembly according to claim 4, characterised in that said permanent magnet (14) is fixed to an extremity portion (12") of said actuating
element (3), so as to be in proximity of said tubing (13) when said actuating element
(3) is inserted in said slot (5).
6. Key-controlled safety switch assembly according to claim 1, characterised in that said detecting device includes a trasponder.
7. Key-controlled safety switch assembly according to claim 1, characterised in that said detecting device further includes a radar/trasmitter assembly.
8. Key-controlled safety switch assembly according to claim 1, characterised in that said locking member (10) includes an electromagnetic bolt (9) having an armature
(10) enclosed by an electromagnet (11).
9. Key-controlled safety switch assembly according to claim 1, characterised in that said safety electric circuit (6) includes a first pair of electric contacts (16,
17) operatively connected to said detection device (13) and moving between an open
position with said actuating element (3) completely extracted and a closed position
with the straight portion (12') of said actuating element (3) completely inserted.
10. Key-controlled safety switch assembly according to claim 9, characterised in that said safety electric circuit (6) includes a second couple of electric contacts (18,
19) series connected to said first pair of electric contacts (16, 17) by a bridge
circuit (18').
11. Key-controlled safety switch assembly according to claim 10, characterised in that said second pair of electric contacts (18, 19) is normally closed when said electromagnet
bolt (9) is not excited and when said actuating element (3) is blocked by said electromagnetic
bolt (9).
12. Key-controlled safety switch assembly according to claim 11, characterised in that the armature (10) of said electromagnetic bolt (9) has a prominence (10') adapted
to interact with a commutation button (21) of said second couple of electric contacts
(18, 19) when said electromagnetic bolt (9) is excited by an external control device.
1. Schlüsselsicherheitsschalter mit
einem würfelartigen Gehäuse (2), das befestigbar ist an einem festen Teil eines Schutzes
oder einer Barriere einer Maschine oder Einrichtung und versehen ist mit einem oder
mehreren Schlitzen (5) mit einem Betätigungselement (3), das befestigbar ist an einem
beweglichen Teil dieses Schutzes und einen geraden Abschnitt (12') aufweist, der in
irgendeinen der Schlitze (5) einsetzbar ist, wobei das Gehäuse (2) mindestens 4 Seiten
aufweist und im Inneren davon einen elektrischen Sicherheitsschaltkreis (6) enthält
zum wahlweisen Öffnen/Schliessen eines allgemeinen Relais oder eines Sicherheitsschalters
der Maschine auf Einsatz/Entnahme des Betätigungselements (3), wobei ein Verriegelungsglied
(10), das ausgebildet ist, um in eine Öffnung (12) eingesetzt zu werden, in dem geraden
Abschnitt (12') angeordnet wird, um wahlweise das Betätigungselement (3) zu verriegeln
in der eingesetzten Stellung in einem Schlitz (5), so lang wie die gefährlichen Teile
der Maschine oder Einrichtung sich bewegen, wobei eine Erfassungsvorrichtung (13),
die ausschließlich vom elektronischen Typ ist, mit Abstand wirkt und ausgebioldet
ist, die Stellung des Betätigungselements (3) zu erfassen, um das Schliessen des elektrischen
Sicherheitsschaltkreis (6) zu erlauben, wobei die Erfassungsvorrichtung (13) einen
permanenten Magneten (14) umfasst, der an dem Betätigungselements (3) befestigt ist
und die Erfassungsvorrichtung (13) weiter mindestens eine Erkennungsvorrichtung (13)
aufweist, die ausgebildet ist, um mit dem permanenten Magneten (14) zusammen zu wirken,
dadurch gekennzeichnet,
dass jede Erkennungsvorrichtung (13) verbunden ist mit einer jeweiligen Seite des Gehäuses
(2), wobei die Schlitze (5) vorgesehen sind auf den mindestens vier Seiten des Gehäuses
(2), jeder Schlitz (5) auf einer anderen Seite des Gehäuses (2), wobei mindestens
eine Erkennungsvorrichtung (13) in der Nähe von jedem Schlitz (5) angeordnet ist und
jede Erkennungsvorrichtung (13) angeordnet ist zwischen der jeweiligen Seite, der
sie zugeordnet ist und dem Verriegelungsglied (9), um mit dem permanenten Magneten
(14) zusammen zu wirken, der an dem Betätigunsgelement (3) befestigt ist, das in irgend
einem Schlitz (5) eingesetzt ist, wobei das Verriegelungsglied (9) zentral in dem
Gehäuse (2) angeordnet ist und das Betätigunsgelement (3) geformt ist, um frei in
den Schlitz (5) mit einer vorbestimmten Toleranz (s) einzugreifen.
2. Sicherheitsschalter gemäß Anspruch 1, dadurch gekennzeichnet, dass der gerade Abschnitt (12') des Betätigunsgelements (3) einen im wesentlichen konstanten
Querschnitt und glatte seitliche Oberflächen hat, um so jedes mechanische Zusammenwirken
mit dem Schlitz (5) zu vermeiden.
3. Sicherheitsschalter gemäß Anspruch 1, dadurch gekennzeichnet, dass in jeder Erkennungsvorrichtung (13) ein Rohr mit magnetischen Kontakten angeordnet
sind.
4. Sicherheitsschalter gemäß Anspruch 3, dadurch gekennzeichnet, daß all die Rohre (13) parallel mit dem Sicherheitsschaltkreis (6) verbunden sind.
5. Sicherheitsschalter gemäß Anspruch 4, dadurch gekennzeichnet, dass der permanente Magnet (14) befestigt ist an einem äußeren Abschnitt (12'') des Betätigungselements
(3), um so in der Nähe von dem Rohr (13) zu sein, wenn das Betätigungselement (3)
in den Schlitz (5) eingesetzt wird.
6. Sicherheitsschalter gemäß Anspruch 1, dadurch gekennzeichnet, dass die Erfassungsvorrichtung einen Transponder umfasst.
7. Sicherheitsschalter gemäß Anspruch 1, dadurch gekennzeichnet, dass die Erfassungsvorrichtung weiter eine Radar/Sender-Einheit umfasst.
8. Sicherheitsschalter gemäß Anspruch 1, dadurch gekennzeichnet, dass das Verriegelungsglied (10) einen elektromagnetischen Bolzen (9) aufweist mit einer
Armatur (10), die von einem Elektromagneten (11) umschlossen ist.
9. Sicherheitsschalter gemäß Anspruch 1, dadurch gekennzeichnet, dass der elektrische Sicherheitsschaltkreis (6) ein erstes Paar elektrischer Kontakte
(16, 17) umfasst, die funktional verbunden sind mit der Erfassungsvorrichtung (13)
und sich zwischen einer offenen Stellung mit dem völlig ausgefahrenen Betätigungselement
(3) und einer geschlossenen Stellung mit dem geraden Abschnitt (12') des völlig eingefahrenen
Betätigungselements (3) bewegen.
10. Sicherheitsschalter gemäß Anspruch 9, dadurch gekennzeichnet, dass der elektrische Sicherheitsschaltkreis (6) ein zweites Paar von elektrischen Kontakten
(18, 19) aufweist, die mit dem ersten Paar der elektrischen Kontakte (16, 17) verbunden
sind mittels einer Brückenschaltung (18').
11. Sicherheitsschalter gemäß Anspruch 10, dadurch gekennzeichnet, dass das zweite Paar von elektrischen Kontakten (18, 19) normalerweise geschlossen ist,
wenn der elektromagnetische Bolzen (9) nicht angeregt ist und wenn das Betätigungselement
(3) gesperrt ist von dem elektromagnetischen Bolzen (9).
12. Sicherheitsschalter gemäß Anspruch 11, dadurch gekennzeichnet, dass die Armatur (10) von dem elektromagnetischen Bolzen (9) einen Vorsprung (10') aufweist,
der ausgebildet ist, um mit einem Umschaltknopf (21) des zweiten Paars von elektrischen
Kontakten (18, 19) zusammen zu wirken, wenn der elektromagnetische Bolzen (9) angeregt
ist von einer äußeren Steuervorrichtung.
1. Ensemble d'interrupteur de sécurité commandé par clé, comprenant un boîtier (2) en
forme de boîte pouvant être ancré à une partie fixe d'une protection ou barrière d'une
machine ou installation et muni d'une ou de plusieurs fentes (5), un élément d'actionnement
(3) pouvant être ancré à une partie mobile de ladite protection et ayant une portion
droite (12') qui peut être insérée dans une quelconque desdites fentes (5), ledit
boîtier (2) ayant au moins quatre côtés et contenant intérieurement un circuit électrique
de sécurité (6) destiné à ouvrir ou fermer sélectivement un relais général ou un interrupteur
de sécurité de ladite machine ou installation lors de l'insertion ou de l'extraction
dudit élément d'actionnement (3), un élément de verrouillage (10) adapté pour être
inséré dans un trou (12) placé dans ladite portion droite (12') pour verrouiller sélectivement
ledit élément d'actionnement (3) dans la position insérée dans une fente (5) aussi
longtemps que les parties dangereuses de la machine ou installation sont en mouvement,
un dispositif de détection (13) qui est exclusivement de type électronique agissant
à distance et qui est adapté pour détecter la position dudit élément d'actionnement
(3) pour permettre la fermeture dudit circuit électrique de sécurité (6), ledit dispositif
de détection (13) comprenant un aimant permanent (14) fixé audit élément d'actionnement
(3), ledit dispositif de détection (13) comprenant en outre au moins un dispositif
de reconnaissance (13) adapté pour coopérer avec ledit aimant permanent (14), caractérisé en ce que chaque dispositif de reconnaissance (13) est associé à un côté respectif dudit boîtier
(2), des fentes (5) étant prévues sur tous les au moins quatre côtés du boîtier (2),
chaque fente (5) sur un côté différent du boîtier (2), ledit au moins un dispositif
de reconnaissance (13) étant placé à proximité de chaque fente (5), chaque dispositif
de reconnaissance (13) étant placé entre le côté respectif auquel il est associé et
ledit élément de verrouillage (9) de manière à coopérer avec ledit aimant permanent
(14) fixé audit élément d'actionnement (3) inséré dans une fente (5) quelconque, ledit
élément de verrouillage (10) étant placé en position centrale dans le boîtier (2),
ledit élément d'actionnement (3) étant conformé pour entrer librement dans ladite
fente (5) avec un jeu prédéterminé (s).
2. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 1, caractérisé en ce que ladite portion droite (12') de l'élément d'actionnement (3) a une section transversale
sensiblement constante et des surfaces latérales lisses de manière à éviter toute
interférence mécanique avec ladite fente (5).
3. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 1, caractérisé en ce que chaque dispositif de reconnaissance (13) est un tube muni de contacts magnétiques.
4. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 3, caractérisé en ce que tous lesdits tubes (13) sont connectés en parallèle audit circuit de sécurité (6).
5. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 4, caractérisé en ce que ledit aimant permanent (14) est fixé à une portion d'extrémité (12") dudit élément
d'actionnement (3) de manière à se trouver à proximité dudit tube (13) lorsque ledit
élément d'actionnement (3) est inséré dans ladite fente (5).
6. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 1, caractérisé en ce que ledit dispositif de détection comprend un transpondeur.
7. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 1, caractérisé en ce que ledit dispositif de détection comprend en outre un ensemble radar/émetteur.
8. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 1 caractérisé en ce que ledit élément de verrouillage (10) comprend un pêne électromagnétique (9) ayant une
armature (10) enfermée par un électro-aimant (11).
9. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 1, caractérisé en ce que ledit circuit électrique de sécurité (6) comprend une première paire de contacts
électriques (16, 17) connectés fonctionnellement audit dispositif de détection (13)
et qui se déplacent entre une position ouverte, dans laquelle ledit élément d'actionnement
(3) est entièrement extrait et une position fermée dans laquelle la portion droite
(12') dudit élément d'actionnement (3) est entièrement insérée.
10. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 9, caractérisé en ce que ledit circuit électrique de sécurité (6) comprend une seconde paire de contacts électriques
(18, 19) connectée en série avec ladite première paire de contacts électriques (16,
17) par un circuit pont (18').
11. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 10, caractérisé en ce que ladite seconde paire de contacts électriques (18, 19) est normalement fermée lorsque
ledit pêne électromagnétique (9) n'est pas excité et lorsque ledit élément d'actionnement
(3) est bloqué par ledit pêne électromagnétique (9).
12. Ensemble d'interrupteur de sécurité commandé par clé selon la revendication 11, caractérisé en ce que l'armature (10) dudit pêne électromagnétique (9) possède une protubérance (10') adaptée
pour interagir avec un bouton de commutation (21) de ladite paire de contacts électriques
(18, 19) lorsque ledit pêne électromagnétique (9) est excité par un dispositif de
commande extérieur.