Abstract:
A base for an electronic card includes at least one slot adapted for accommodating an electronic card with an extraction lever installed rotatably in relation thereto and adapted for pivoting between a first position and a second position. The lever has a support end adapted for coming to rest on a support element of the base in order to extract the electronic card from the base when the lever changes from the first to the second position. The support element has a first state in which the extraction lever does not bear on the support element when changing from the first position to the second position, and a second state, in which the lever bears on the support element when changing from the first to the second position. This creates a movement for extraction of the card through the support end along a support direction.

Description:
TECHNICAL FIELD 
     This invention relates in general to electronic card extractors. 
     More particularly, this invention relates to electronic card extractors for avionic equipment items of an aircraft. 
     BACKGROUND 
     The avionic equipment items of an aircraft are made up of computers having the form of electronic cards installed in units or cabinets, connected to the electrical bundle of the aircraft. In practice, the electronic cards are installed by one of their edges into a slot provided for this purpose on a base installed in a unit. The back of the unit has a plurality of connectors disposed perpendicular to the base, so as to connect electrically the electronic cards installed on the base by an edge perpendicular to and immediately adjoining the edge installed in the slot of the base. 
     Usually, in a standard device comprising electronic cards, in order to remove an electronic card it is necessary to make sure to have cut off the electrical supply of the electronic card in order to avoid any damage to the electronic components before actuating the extractor in order to extract the card. 
     In avionic equipment items, there are modular equipment items wherein one of the sought objectives is to retain the availability of various avionic functions even when a given electronic card is removed. In concrete terms, it is a matter of being able to remove cards independently of one another and to see to it that the equipment is able to provide a given function despite the absence of one or more electronic cards. 
     In practice, in order to extract an electronic card, the operator sends out an extraction request on a central computer for a given card. The other cards then are reconfigured in order to be able to function without the chosen card and the power supply of the latter is cut off. A visual indicator tells the operator that he may extract the card. 
     Nonetheless, the risk remains that the operator will not remove the card on which the extraction request has been implemented, but another card. An erroneous extraction may damage the card in question. In addition, malfunctions of the system may occur since the system has not been reconfigured to operate without the card extracted by error. 
     The problem thus is to make extraction of the card subject to the modular preparation of the other electronic cards and to the cutoff of current thereto. 
     More generally, the problem therefore is to prevent incorrect or erroneous extractions of the electronic cards. 
     In order to be extracted, the cards are provided with extractors in the form of a lever making it possible to reduce an extraction force applied on the lever in order to contribute toward extracting the card. 
     In fact, the evolution of the number of components on the electronic cards led to the increase of the number of contacts between the cards and their connectors. The contact pressure on each of the cards is such that it is necessary to provide an extractor. In practice, an extraction may require a force ranging up to 350 N. It is understood that without the aid of an extractor, it is impossible to extract the card. 
     SUMMARY 
     Based on these observations, the invention proposes a base for an electronic card comprising at least one slot adapted for accommodating an electronic card with an extraction lever installed rotatably in relation thereto and adapted for pivoting between a first position and a second position, the lever having a support end adapted for coming to rest on a support element of the base in order to extract the electronic card from the base when the lever changes over from the first to the second position, the support element having a first state in which the extraction lever does not bear on the support element when changing over from the first position to the second position, and a second state, in which the lever bears on the element when changing over from the first to the second position, the rotation of the lever from the first position to the second position then bringing about a movement for extraction of the card through resting of the support end of the lever on the support element along a support direction. 
     The invention thus proposes to make the support surface for the extraction lever inoperative, so as to make the latter inoperative through lack of support surface when that is necessary. In other words, since the efficacy of the lever is dependent on the presence of a support surface, the fact of making the latter inoperative prevents activation of the lever and therefore stands in the way of any erroneous extraction of the card. 
     This ensures a greater reliability during maintenance operations. 
     According to one possible advantageous characteristic of the invention, the support element is installed free in translation along the support direction, and the changeover from the first to the second state is accomplished by a mechanical blockage of the support element in translation in a position in which the support end of the lever bears on the said element during rotation of the lever from the first position to the second position, then bringing about a movement for extraction of the card. 
     In this way, the number of mechanical parts in motion advantageously is limited. 
     According to possible advantageous characteristics of the invention, combined if need be:
         the support element is movable between a first position in which it is not in the path of the support end of the lever when the latter changes over from its first to its second position, and a second position in which the support element is in the said path of the support end of the lever, the changeover from the first to the second state being accomplished by a movement and a mechanical blockage of the support element from the said first position to the said second position;   the support element is movable in translation along the support direction;   the support element is movable along a direction more or less perpendicular to the support direction;   the mechanical blockage is accomplished with the aid of an electromagnet.       

     According to another aspect, the invention relates to an extraction device comprising at least one electronic card having a lever having a support end adapted for coming to rest on a support element and a base such as described above. 
     According to an advantageous aspect, the extraction device comprises visual means indicating that the support element is in the second state. 
     According to another aspect, the invention relates to an electronic card extraction device comprising a plurality of interconnected cards and control means adapted for:
         receiving an extraction request for a given card,   reconfiguring the other cards so as to provide the function or functions of the card to be extracted,   sending a signal to the support element of the selected card to change over from the first to the second state,   indicating by a visual indicator that the card is ready to be extracted.       

     According to another aspect, the invention relates to a method for extraction of an electronic card with the aid of an extraction device such as described above, comprising the following steps:
         sending out an extraction request for a given card,   identifying with the aid of the visual indicator that the card is ready to be extracted,   extracting the card by causing the lever to change over from the first to the second position.       

     According to another aspect, the invention relates to an aircraft equipped with a base and/or an extraction device and/or a control device such as described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The explanation of the invention now will be continued with the detailed description of two exemplary embodiments, given below by way of illustration and non-limitative, with reference to the attached drawings. Thereon: 
         FIGS. 1   a  to  1   c  show the operating principle of an extraction lever for an electronic card in general; 
         FIGS. 2   a  to  2   c  show the operating principle of an extraction lever for an electronic card according to the invention; 
         FIG. 3  is a side view of an alternative embodiment of an extraction device for an electronic card according to the invention; 
         FIG. 4  is a side view of another embodiment of an extraction device for an electronic card according to the invention. 
         FIG. 5  is a schematic view of a control device connected to a plurality of bases and cards. 
     
    
    
     DETAILED DESCRIPTION 
     Generally speaking, the same numerical references are used in the description of the attached Figures for identical or similar elements. 
       FIGS. 1   a ,  1   b  and  1   c  schematically show in a side view an electronic card  1  installed by its lower edge in a slot  2  provided for this purpose in a base  3  installed in a unit  4 . The back of unit  4  has a connector  5  disposed perpendicular to the base in the same plane as slot  2  so as to connect electrically the electrical contacts of the electronic cards disposed on an edge perpendicular to and immediately adjoining the edge installed in the slot of the base. 
     On  FIGS. 1   a  to  1   c  the electrical contacts of card  1  have been shown, the other cards, not visible, being installed in the same way. 
     Card  1  has, at the end opposite electrical contacts  6 , a lever  10  installed rotatably on card  1  through a pivot  11  perpendicular to the card and to the longitudinal direction of the latter. 
     As visible more particularly on  FIGS. 1   b  and  1   c , when the lever is pivoted around pivot  11  from a first position ( FIG. 1   a ) to a second position ( FIG. 1   c ), a support end  12  of the lever bears on an exterior face of base  3  forming a support surface, reducing the force applied to the opposite end of the lever in order to convert it into a force for extraction of the card from its connector  5 . 
     The contact forces between contacts  6  and connector  5  are such that the use of an extraction lever  10  is necessary in order to extract card  1  from connector  5 . The invention benefits from this finding by proposing to provide or not provide a support surface for the lever, in this way allowing or precluding extraction of the card. 
     A first embodiment of an extraction device according to the invention is visible on  FIGS. 2   a  to  2   c . According to the same mechanical principle as on  FIGS. 1   a  to  1   c , the extraction device comprises an extraction lever  10  for electronic card  1  installed along pivot  11  in relation to the card, so that it may pivot between a first position and a second position. The movement for extraction of the card is dependent on the presence of a support surface for the support end  12  of the lever. 
     As visible on  FIGS. 2   a  to  2   c , the base according to the invention has a support device  20 . The latter comprises a support plate  21  integral with a rod  22  at least partially ferromagnetic and installed translatably in base  3  between a first retracted position such as visible on  FIG. 2   a  and a second position referred to as support such as visible on  FIGS. 2   b  and  2   c . Translation from the first position to the support position is controlled by an electromagnet  23  composed of the ferromagnetic part of rod  22  on which there is installed an electrical coil  24  supplied by an electrical circuit  25  subjected to a DC voltage. Circuit  25  may be interrupted with the aid of a switch  26 . The ferromagnetic part of rod  22  and coil  24  jointly form an electromagnet. 
     When switch  26  is closed, coil  24  generates an electromagnetic field acting on the ferromagnetic part of rod  22 , thus causing it to change over from the retracted position visible on  FIG. 1  to the support position visible on  FIG. 2   b  in which support plate  21  is moved forward so that support end  12  of lever  10  bears on the support plate. Lever  10  then brings about a movement for extraction of the card during its rotation around pivot  11  as visible on  FIG. 2   c.    
     In this way, advantageously, since the extraction of the card is dependent on the presence of the support surface for lever  10 , any untimely extraction is prevented as long as support element  21  is not in the second position referred to as support. 
     An alternative embodiment is shown on  FIG. 3 . 
     According to the same principle as set forth on  FIGS. 2   a  and  2   c , in this embodiment a support device  30  is installed in base  3 . This device comprises a support plate  31  integral with a rod  32  installed translatably in base  3  and integral with its end opposite a stop plate  33 . A spring  34  comes to rest on the free face of plate  33  so as to come to flatten the latter against two stops  35  projecting from base  3 . 
     According to the same principle as set forth for  FIGS. 2   a  to  2   c , rod  32  has a ferromagnetic portion around which there is installed an electrical coil  36  connected to an electrical circuit  37  subjected to a DC voltage. The electrical circuit  37  may be interrupted with the aid of a switch  38 . The ferromagnetic part of rod  32  and coil  36  jointly form an electromagnet. 
     In operation, device  30  has a rest position such as visible on  FIG. 3 , in which spring  34  comes to flatten stop plate  33  against stops  35 , support plate  31  then being in a position referred to as support for end  12  of lever  10 . If the latter came to be lowered while switch  38  is open, support plate  31  would retract into device  30  by compressing spring  34 . The extraction lever then would not bear on support plate  31  and there would be no effect of movement for extraction of the card for lack of support surface. 
     When switch  38  is closed, coil  36  generates an electromagnetic field around the ferromagnetic part of shaft  32 , thus blocking the assembly in translation, which immobilizes support plate  31 . Lever  10  then may be lowered until its support end  12  comes to rest on support plate  31  from now on immobilized, and it then brings about a movement for extraction of the card through support on this plate in a manner similar to the extraction illustrated on  FIGS. 2   b  and  2   c.    
     Spring  34  and coil  36  forming an electromagnet with shaft  32  are sized so that a minimal voltage is required to block translation of the assembly when switch  38  is closed. 
     Another embodiment is shown schematically on  FIG. 4 . In this embodiment, an electronic card  1  similar in every respect to the electronic cards such as described above and having a lever  10  with a support end  12  is adapted for cooperating with a locking mechanism  40 . The latter has a lock  41  fastened to a base, not shown, and in which a slot is provided to accommodate electronic card  1  in a manner analogous to the embodiments described above. It is a matter of an electromagnetic lock connected to an electrical circuit, not shown, and similar in every respect to the electrical circuit described above. Electromagnetic lock  41  has a feeler gauge  42  controlled in translation by an electromagnet shown disposed inside the lock. The locking mechanism  40  is fastened onto the base (not shown) at the level of support end  12  of the lever, when card  1  is inserted therein. The feeler gauge  42  is adapted for moving in translation between a first position in which it is retracted completely into the body of lock  41  and a second position, such as shown on  FIG. 4 , in which the feeler gauge is in the path of support end  12  when the lever pivots around pivot  11 . Feeler gauge  42  then serves as support element for support end  12  of the lever, then bringing about a movement for extraction of the card in a manner analogous to the extraction shown on  FIGS. 2   b  and  2   c . In an embodiment not shown, the lock is fastened in a machining provided for this purpose on the base. 
     According to an advantageous aspect of the invention able to be applied to all the embodiments described above, in a device comprising a plurality of interconnected electronic cards (not shown), visual indication means are provided on the card or close thereto in order to indicate to the operator that the support means are activated. It is a matter, for example, of a light-emitting diode connected to the power supply circuit of the electromagnet and which indicates whether the latter is carrying current. 
     According to the embodiments, the operator knows, depending on whether the diode is on or off, whether the card is ready to be extracted. 
     In practice, the switches of the power supply circuits of the embodiments of the invention described above are controlled by a control device  50  for the extraction of electronic cards. In a device comprising a plurality of interconnected electronic cards  52 , this control device  50  is adapted for receiving from the operator an extraction request for a given electronic card, and for then reconfiguring the other cards so that the latter provide the function or functions of the card to be extracted. The device then sends a signal to the corresponding switch of the card to activate the support means and cause them to change over to a state in which the lever bears on the support element. At the same time, if a visual indicator  51  is present, the latter is swung to a state in which it indicates to the operator that the chosen card is ready to be extracted. 
     In practice, the operator sends out an extraction request for a given card on the control device  50 . He then identifies, with the aid of the visual indicator  51 , that the card in question is ready to be extracted and, the support means being activated, he acts on the lever so as to cause it to change over from the first to the second position such as described above in order to extract the card in question. 
     Numerous other variants are possible according to circumstances, and in this regard it is recalled that the invention is not limited to the examples described and shown.