WO2009153456A1

WO2009153456A1 - Structure of a computer for an aircraft and of the associated removable modules

Info

Publication number: WO2009153456A1
Application number: PCT/FR2009/000725
Authority: WO
Inventors: Jean-Clair Pradier; Bertrand Maes
Original assignee: Sagem Defense Securite
Priority date: 2008-06-17
Filing date: 2009-06-17
Publication date: 2009-12-23
Also published as: FR2932585B1; FR2932585A1

Abstract

The invention relates to an aircraft computer comprising a box (1) with a casing (50) into which the removable modules (10, 20) are inserted, each of the modules consisting of: a printed circuit board (60) carrying electronic components; a stiffening frame (61) made of metal positioned against the printed circuit board on the same face thereof as carries the electronic components, said stiffening frame comprising a longitudinal member (62) which extends along a first side of the printed circuit board, two external arms (63) which extend from the longitudinal member along two adjacent sides of the printed circuit board and at least one central arm (64) which extends from the longitudinal member parallel to the external arms; and a sheet metal cover (65) having a flat which covers a free face of the stiffening frame, said cover being extended by a return (68) disposed at a right angle, which covers the longitudinal member (62) of the stiffening frame (61) and ends in a lip (70) that comes into contact with the cover of an adjacent module or the casing of the box.

Description

Structure of an aircraft computer and associated removable modules.

The invention relates to an aircraft computer, in particular its structure and that of the associated removable modules.

BACKGROUND OF THE INVENTION

The aircraft are equipped with various computers to perform the various functions enabling the aircraft to fulfill its mission. Among calculators, mention may be made of flight computers, which are responsible for maneuvering the various aerodynamic control surfaces in response to orders from the pilot or an autopilot, the propulsion computer, responsible for managing the thrusters of the aircraft, the braking and grounding computer of the aircraft.

In the classical architectures, each function is ensured by a dedicated calculator. This total segregation makes it possible to prevent a failure of one of the computers from leading to the loss of another function.

However, this architecture is heavy and cumbersome.

Sometimes some of the functions are grouped together and provided by the same calculator. For example, there are calculators ensuring both the braking of the aircraft and its direction on the ground by means of the steerable wheels of the undercarriage. However, failure of the computer causes the simultaneous loss of both functions.

More recently, it has been proposed a modular architecture called IMA (for Integrated Modular Avionics), in which each of the functions is provided by a dedicated module, all modules being received so removable in a single housing, each module having its own power supply, its own processing means and its own input / output means.

It is therefore expected that the aeronautical computers will present more and more a modular structure.

In particular, it is known, in particular from document FR 2 728 427, aircraft computers comprising a housing with a carcass in which removable modules are inserted, each of the modules comprising:

- a printed circuit board carrying electronic components;

- A metal stiffening frame disposed against the printed circuit board on the side of the face thereof which carries the electronic components, the stiffening frame having a spar extending along a first side of the circuit board printed, two outer arms extending from the spar along two adjacent sides of the printed circuit board, and at least one central arm extending from the spar parallel to the outer arms.

In general, such modules are covered by a sheet metal cover having a plant which covers a free face of the stiffening frame and which protects the electronic components. The dish of the hood contributes to give the assembly a great mechanical resistance. Moreover, the contact of the cover with the stiffening frame ensures a thermal and electrical continuity between these two elements. The frame thus forms a radiator which transmits by heat the heat to the hood. In addition, the connectors that connect the module to the bottom boards of the housing can advantageously take place between the ends of the arms so that they naturally close the internal volumes defined between the arms and closed on one side by the circuit board printed and on the other side by the hood.

Electrical continuity should be ensured between the cover of a module and that of an adjacent module, as well as between these covers and the casing of the housing. For this purpose, it is known from US4872212 to achieve this continuity by providing on the hood an amount forming a front face of the module, the amount carrying conductive strips of elastic metal, for example a beryllium copper, the strips coming to establish a electrical contact between two adjacent modules.

OBJECT OF I / INVENTION

The invention aims to provide a modular computer structure particularly simple to manufacture, and wherein the electrical continuity between the modules and the housing is provided very simply and very economically.

BRIEF DESCRIPTION OF THE INVENTION

According to the invention, there is provided an aircraft computer comprising a housing with a carcass in which removable modules are inserted, each of the modules comprising:

- a printed circuit board carrying electronic components;

- a metal stiffening frame disposed against the printed circuit board on the side of the face thereof which carries the electronic components, the frame stiffener having a spar extending along a first side of the printed circuit board, two outer arms extending from the spar along two adjacent sides of the printed circuit board, and at least one arm central extending from the spar parallel to the outer arms;

- A sheet metal hood having a flat which covers a free face of the stiffening frame.

According to the invention, the sheet metal hood is extended by a right angle return which covers the longitudinal member of the stiffening frame and which ends with a flap which comes into contact with the cover of an adjacent module or the casing of the housing.

This ensures very easily an electrical continuity between the covers and the casing of the housing. Moreover, the introduction face of the housing modules is, when all the modules are in place in the housing, fully closed by the returns of the covers. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood in the light of the figures of the appended drawings, among which:

- Figure 1 is a perspective view of a housing of a computer according to a particular embodiment of the invention, capable of managing the functions of braking, maneuvering the landing gear, and ground orientation;

- Figure 2 is a sectional view of the housing at the master module; Figure 3 is a block diagram explaining the operation of the housing of Figures 1 and 2; - Figure 4 is a perspective view of a housing according to a particular embodiment of the invention;

- Figure 5 is a sectional view of the housing and one of the modules along the line V-V of Figure 4;

FIG. 6 is an exploded perspective view of one of the dedicated modules of the housing of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 and 2, the computer of the invention comprises a housing 1 comprising several locations for removably receiving various modules, including:

a master module 10;

- Several dedicated modules 20 (only one is shown here), including, in the application envisaged here, a module dedicated to braking, a module dedicated to the maneuver landing gear, a module dedicated to the ground orientation of the aircraft , a module dedicated to the detection function of the aircraft. Each of the modules consists essentially of a printed circuit board carrying, on one of its edges, an internal power and communication connector referenced 11 on the master module 10 and 21 on each dedicated module 20, and a connector input / output referenced 12 on the master module 10 and 22 on each dedicated module 20.

The power supply and internal communication connectors 11, 21 cooperate, when the modules are in place in the housing, with homologous connectors 14, 24 arranged on an internal power supply and communication card 3 extending at the bottom of the housing. . The internal power and communication card 3 is connected by a connector not visible here to an external power supply of the aircraft, so that energy is transmitted to the modules by the card 3. Similarly, the input connectors / output 12,22 cooperate, when the modules are in place in the housing, with matching connectors 17,27 arranged on an input / output card 5 also extending at the bottom of the housing. The input / output card 5 is electrically connected to an interconnection card 6 which carries external connectors 8/18/28 and carries filtering members for filtering the signals or the power coming from outside the housing .

In FIG. 2, the supports that hold the cards 3.5 and 6 at the bottom of the case have not been shown, for the sake of clarity.

The description is now continued with reference to FIG. 3 on which the internal power supply and communication card 3 on the one hand and the input / output 5 and interconnection cards 6 on the other hand have been represented on the one hand. and other modules for clarity. The interconnection card 6 carries a power connector 8 through which the power from the aircraft power supply circuit is supplied to the casing 1. The power passes through the input / output card 5 via the connectors 12 , 17, to a power management member 13 disposed on the master module 10. The power management member 13 receives the power of the aircraft, the caliber, and redistributes it to the modules dedicated by 20 lines power 15 worn by the 3. The power management device 13 preferably comprises a filter, a transformer, and selective cut-off devices 16, for example controlled switches, making it possible to selectively authorize the power supply. supply or on the contrary to cut the power supply of each of the dedicated modules 20.

The power management unit 13 continuously monitors the impedance of each power line 15 leading to each of the dedicated modules, and if the impedance of one of the power lines 15 becomes low, which means that the line concerned is open, the power management member 13 then controls the corresponding selective cutoff member 16 to cut off the supply of the dedicated module 20 concerned. Similarly, if the impedance of one of the power lines 15 becomes significant, which means that the dedicated module 20 is short-circuited, the power supply of the dedicated module concerned is cut off. The faulty dedicated module is then disabled and the function provided by this module ceases to be fulfilled.

The power and internal communication card 3 also carries an internal communication network 9, symbolized here in dotted lines, which makes it possible to connect each of the modules 10, 20 together so that the dedicated modules 20 can exchange information with the module. master 10. The internal communication network 9, like the power lines 15, are here connected to the modules by the same connector, referenced 11 for the master module 10 and 21 for the dedicated modules 20. The housing comprises a connector 18 for the connection of the master module 10 with a data bus of the aircraft, for example an ARINC bus 429 by means of which digital information such as the speed of the aircraft can be supplied to a central unit 29 implanted on the master module. The connector 18 is carried by the interconnection card 6. The data are then transmitted to the filter card 5 which carries the connector 17 by which these data are transmitted to the master module 10.

The interconnection card 6 also carries various analog connectors 28 which allow each dedicated module 20 to receive analog data from sensors of the aircraft, and to send analog commands to various components controlled by the dedicated module concerned. .

For example, the module dedicated to braking receives signals from the brakes, such as the pressure imposed by the pistons on the brake discs, the signals from the potentiometers on the brake pedals of the pilot and the co-pilot, a signal coming from the parking brake control, and returns orders to the braking servovalves ... The module dedicated to the operation of the undercarriages receives signals from the various position sensors associated with the movable elements to maneuver (undercarriages, hatches, hooks). locking ...) and sends commands to the control valves of the operating cylinders.

The data are filtered by filtering elements 23 arranged on the interconnection card 6, and are transmitted to the interconnection card 5 which interface each of the connectors 28 to the dedicated module concerned.

It will be noted that the intermodule connections provided by the card 3 are strictly segregated from the external connections of the computer 8, 18, 28 carried by the interconnection card 6.

The dedicated modules 20 essentially comprise input / output management modules 25. They are adapted on the one hand to receive analog signals from the connectors 28, to format them numerically, to group them, and to make them available via the communication connector 21 for all the modules of the computer via the internal communication network 9.

These data are used by computer processing means 29 carried by the master module 10, which implements the processing necessary for the execution of all the functions provided by the computer of the invention. the computer processing means 29 generate commands that are sent back to the dedicated module 20 concerned. This order is transformed into an analog signal and sent back to the input / output means 25 of the dedicated module 20 concerned. The input / output means 25 format the order into an analog signal which is sent to the corresponding actuator via the associated connector 28.

Thus, the computer processing means 29, as well as the power management means 13, are grouped together on the master module 10. The dedicated modules 20 comprise only input / output means 25 comprising logic means of low level, intended solely to ensure the conditioning and transmission of input / output signals. The dedicated modules 20 are therefore simpler than their equivalents in the IMA architecture which each include their own power management device and their own computer processing means.

According to one particular aspect of the invention, the dedicated modules 20 are equipped downstream of the communication connector 21 with selective unsubscription means by the master module. In this case, the selective unsubscribe means include tri-state input / output buffers 26, including one-way state, one-way state, and a high-impedance state. For example, one can use buffers of 74HC245 type. The input / output buffers 26 are controlled by the master module 10 via the internal communication network 9 as follows. The input / output buffers 26 are a priori in one of the passing states, depending on the direction of the data flowing. The master module 10 continuously monitors the coherence of the data flowing on the internal communication bus 9 of the communication card 6. In the event of inconsistency of the data coming from one of the dedicated modules 20, the associated buffer 26 is placed by the master module 10 in the state of high impedance. Thus, the dedicated module concerned is unsubscribed from the internal communication bus 9.

To ensure complete isolation of the function thus inhibited, the software executed by the computer processing means 29 of the master module 10 is preferably partitioned so that the part of code corresponding to the inhibited function is rendered inoperative and can no longer be executed.

According to another particular aspect of the invention, each of the dedicated modules 20 comprises inhibition means 31 adapted to inhibit the dedicated module concerned in response to inhibition commands generated outside the box 1 and transmitted to the dedicated module by the connector 28 concerned. Thus, if the master module 10 failed to activate a function inadvertently, it is possible to inhibit from the outside the dedicated module 20 concerned so that it does not send orders outside. actuating the associated members. In practice, the selective inhibition means 26 comprise a programmable logic circuit of the FPGA type, thus low-level logic, inexpensive. The inhibiting means 31 are adapted to prevent any sending of orders by the inhibited dedicated module to the associated actuators.

The architecture of the invention has several advantages over known architectures: it uses a master module 10, relatively sophisticated, but can be produced in series, which lowers manufacturing costs. This master module is identical whatever the aircraft envisaged. Only the software implemented by the computer processing means 29 is specific. However, we can consider a standard software, provided that we design this software with extensive settings options. It also uses several modules each dedicated to a specific function, very simple so little expensive. Each of the dedicated modules can be extensively standardized. For example, the braking module can be adapted to handle four brakes, two braked wheels carried two by two on the main landing gear. This type of braking module can then be used for almost all business aircraft, regional aircraft, as well as A320 or B737 single-aisle airliners. Each dedicated module comprises in series a determined number of inputs / outputs, sufficient in practice to cover all applications envisaged.

Finally, it uses a box whose size is easily adaptable to the number of modules to receive.

The housing and the associated background cards can be provided in several standard sizes, functions of the number of modules to receive.

As is obvious to those skilled in the art, the computer of the invention does not offer a total segregation of functions, since the power supply and computer processing are provided by the single master module 10 for all dedicated modules. However, the failure of a dedicated module can be circumscribed by interrupting its power supply and isolating it from the communication bus, so that this loss does not result in the loss of the functions performed by the other dedicated modules. Thus, the functions provided have a high availability. To further improve the availability of all the functions provided, it will be possible to integrate two master modules 10 into one box, or to provide two computers according to the invention in the same aircraft. The operation of the housing of the invention is now explained, we will now describe in detail a particular embodiment of manufacture of such a housing in connection with Figures 4 to 6. In Figure 4, there is recognized the housing 1, which comprises a carcass 50 sheet metal closed on one side by an attached bottom 55 (not visible here, but visible in section in Figure 5) which carries the connectors of the housing, so the analog connectors 28 that we see here exceed. Fixing feet 51 are attached to the sides of the carcass 50 to allow the attachment of the housing 1 to the structure of the aircraft. The housing 1 is open on a face opposite to the bottom 55, two of the edges of this face being cut to include fastening tabs 52, folded here inwards, which allow to fix the modules 10, 20 when they are in position. placed in the housing 1 by means of screws 53. Guide rails are fixed inside the housing 1 to guide the modules 10,20 when they are put in place. The 3,5,6 cards are received at the bottom of the casing 1.

Each of the dedicated modules 20 comprises a printed circuit board 60 which is screwed onto a stiffening frame

61 made here in aluminum and which comprises a stiffener

62 of which extend two outer arms 63 and a central arm 64. The stiffener 62 extends along the side of the printed circuit board 60 which is opposite the side thereof receiving the connectors 21,22. As for the outer arms 63, they extend along the other two sides of the printed circuit board. The connectors 21, 22 each extend between the ends of one of the outer arms 63 and the central arm 64 to project from the printed circuit board 60 and cooperate with the corresponding connectors 4.7 respectively carried by the power supply card 3 and the communication card 6 at the bottom of the housing. It will be noted that the electronic components by the printed circuit board 60 extend on the side of the card that receives the stiffening frame 61.

This side is covered with a sheet metal cover 65 which comprises a plate 66 which bears against the outer face of the arms 63, 64 of the stiffening frame 61 and which is fixed thereto by means of screws 67. a thermal and electrical continuity between the stiffening frame 61 and the cover 65. The plate 66 conceals the electronic components carried by the printed circuit board 61. The plate 66 is extended by a return at right angles 68 which covers the stiffener 62 of the frame stiffener 61 and which has two holes 69 to pass the screws 53 for fixing the module to the housing 1. The return 68 extends beyond the printed circuit board 60 and ends with a flap 70 slightly outwardly so that when the module is in place in the housing, the flap 70 comes into contact with the cover of the adjacent module, to achieve electrical continuity between the covers of all the modules plugged into the housing 1. To assure the electrical continuity between the covers 65 and the casing 50 of the casing 1, it includes flaps similar to those of the covers 65 which extend along the sides 71,72 referenced in Figure 4 to come into contact with the covers of modules adjacent to these sides. As can be seen in FIG. 4, the returns 68 of the covers 65 close the open face of the casing 1.

The flaps 70 are naturally elastic in bending and are shaped so that when the module is put in place, the flap is compressed and flexed slightly, which ensures that the mechanical contact with the adjacent module cover, and therefore the electrical continuity , will be well insured with the adjacent module even in case of vibrations. To facilitate the extraction of the modules, the stiffening frame 61 has two handles 73 which extend in the extension of the outer arms 63, on the other side of the stiffener 62. It is seen in Figure 4 the handles 73 which protrude from the housing 1, facilitating the manipulation of the modules.

As for the connectors, they are held by screws 77 which pass through the cover 65 and the printed circuit board 60. It will be noted that they close the internal volumes delimited between the arms of the stiffening frame 61, the printed circuit board 60 and the hood 65.

Thus, the mechanical structure of each module is here particularly simple. Added to the printed circuit board 60 a stiffener 61 also serving as a radiator and a cover 65 in cut sheet metal, all assembled simply by means of screws. Three of the sides of the printed circuit board bear against the stiffening frame, while the fourth side is connected to the cover by the connectors. The assembly thus formed is particularly rigid and light. What has just been said here for the dedicated module 20 is of course valid for the master module 10. The invention is not limited to what has just been described, but on the contrary covers any variant within the scope defined by the claims. In particular, the connector 18 connecting the housing 1 to the data bus of the aircraft and the power connector 8 can be grouped in one and the same connector.

In any case, it is important that the data coming from the data bus of the aircraft and the power coming from the aircraft are filtered in order to protect the case from any electromagnetic disturbances.

Claims

An aircraft computer comprising a housing (1) with a housing (50) into which removable modules (10, 20) are inserted, each of the modules comprising: a printed circuit board (60) carrying electronic components;

- a metal stiffening frame (61) disposed against the printed circuit board on the side of the face thereof which carries the electronic components, the stiffening frame having a spar (62) extending along a first on the side of the printed circuit board, two outer arms (63) extending from the spar along two adjacent sides of the printed circuit board, and at least one central arm (64) extending from the spar parallel to the outer arms; a cover (65) made of sheet metal having a plate which covers a free face of the stiffening frame, characterized in that the sheet metal cover (65) is extended by a right-angle return (68) which covers the frame spar (62). stiffener (61) and which terminates in a flap (70) which comes into contact with the cover of an adjacent module or the casing of the housing.

An aircraft computer according to claim 1, wherein the stiffening frame (61) has handles (73) projecting from the spar (62) on the side opposite the arms.

3. Calculator according to claim 1, wherein the housing comprises at least one base board (3.6) with connectors for its connection to each of the modules, each removable module (10,20) having a connector corresponding which extends along one side of the printed circuit board (60) between the ends of two arms.