FR2786326A1 - Secondary distribution cabinet for aeroplane's electric power system, comprises multi-layer printed circuit board, with circuit-breakers controlling each outgoing circuit - Google Patents

Abstract

The power system is based on a primary control point in the pilot's cockpit, from which feeder circuits (22) run to secondary cabinets (14) distributed through the aircraft, each controlling a gorup of 4 or more utilisation points via secondary feeder circuits all emanating from a plug connector (46) on the cabinet's printed circuit board (30). Each such outgoing circuit is protected by a circuit-breaker (36,38,40,...) rated between 1 and 15 A, fixed mechanically by tags (82) to the board, with its reset button (36C, etc.) projecting through the cabinet's front-plate (50). As well as the power connections (36A,36B, etc.) to the incoming supply track and the outgoing circuit, each circuit-breaker has on/off indicating contacts connected (36D, etc., 54) to tracks leading to a control circuit board (52) parallel with the main board and equipped with a plug connector (56) having a cabled connection to a consolidating display panel in the cockpit. The printed circuit board has, typically, 6 layers, carrying on one the incoming power tracks, over two layers allotted to the outgoing circuit connections, and two for the state monitoring connections. The lowest layer functions as a heat sink. Each upper layer is perforated where necessary to allow conductor access to those below.

Description

 The present invention relates to a secondary electrical power distribution cabinet of an aircraft, of the type comprising electromechanical protection members intended to be installed in an electrical power supply network of an aircraft between a main power distribution cabinet and functional organs of the aircraft.

 In current aircraft, the electrical supply network comprises a main electrical power distribution cabinet, supplying the functional organs of the aircraft, through a set of protective members. The protection members are arranged, in sub-groups, in several secondary power distribution cabinets to which the corresponding functional members are connected. Each secondary cabinet is supplied from the main cabinet by a power cable common to all the protection members of the same sub-group.

 The electrical energy comes from the main electrical power distribution cabinet, which supplies the entire device. This main cabinet is commonly referred to as an electrical core. It ensures the management of the electrical supply of the device from the electrical power supplied by one or more electric generators, batteries, and possibly other emergency generators. The main power distribution cabinet mainly comprises power relays, circuit breakers, current sensors and power interconnection bars.

 It is connected, downstream, to one or more secondary power distribution cabinets which form connection bays for all of the functional organs of the apparatus. Each secondary cabinet comprises, for each functional member, an electrical protection member such as a circuit breaker of suitable power.

 The circuit breakers are carried by a front face of the secondary cabinets. Their reset button is accessible from the aircraft cockpit. The circuit breaker wiring is made up, on the one hand, of metal power supply bars, connecting these to the main distribution cabinet, and, on the other hand, flexible conductors connecting each circuit breaker to a functional member from the plane.

 Thus, for each functional member, at least one flexible conductor travels through the aircraft from the associated circuit breaker to the corresponding functional member.

 This architecture of the supply network requires a great deal of complexity in the secondary distribution cabinets and a very long assembly time thereof. In addition, the bundles of conductors connecting all of the functional members to the secondary cabinets have a high mass.

 The object of the invention is to make it possible to reduce the weight and the assembly time of the electrical power supply network of an aircraft and therefore the cost of ownership.

 To this end, the subject of the invention is a secondary distribution cabinet for the electrical power of an aircraft, of the aforementioned type, characterized in that it comprises a printed circuit on which the protection members are installed, which circuit includes power tracks to which the protection members are connected, and in that it comprises means for electrical connection of the power tracks, on the one hand, to a power cable coming from the main power distribution cabinet and, on the other hand, to each of the protected functional organs.

According to particular embodiments, the secondary distribution cabinet includes one or more of the following characteristics:
- each electromechanical protection device is a circuit breaker
each protection member comprises terminals for electrical connection to the power tracks of the printed circuit, and there are means for mechanical fixing of each protection member to the printed circuit, which mechanical fixing means are independent of the terminals for electrical connection;
said mechanical fixing means comprise a strap overlapping each protection member, which strap comprises, at its ends, on either side of the protection member, lugs for mechanical connection to the printed circuit;
each protection member comprises a state contact, representative of the state of the protection member, and the printed circuit comprises state control tracks to which said state contacts are electrically connected, the printed circuit comprising means for connecting the state control tracks to means for making the state of the protection organs available;
the printed circuit is a multilayer printed circuit, at least one layer carrying only power tracks and at least one layer carrying only state control tracks;
printed circuit is a multilayer circuit, at least one layer carrying power tracks for the connection of a power cable to the protection members and at least one layer carrying power tracks for the connection of the protection members to the functional members protected; and
the printed circuit comprises a thermal drainage layer (110).

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which:
FIG. 1 is a schematic view of an electrical power supply network of an aircraft according to the invention;
FIG. 2 is a schematic view in cross section of a secondary power distribution cabinet;
FIG. 3 is a perspective view of a circuit breaker; and
FIG. 4 is an exploded perspective view of the printed circuit of the secondary distribution cabinet according to the invention.

 The network 10 shown in FIG. 1 comprises a cabinet 12 for the main distribution of electrical power connected to four cabinets for the secondary distribution of power denoted 14, 16, 18 and 20.

 Two of the secondary cabinets 14, 18 are arranged at the front of the device, respectively to the right and left of it, while the other two cabinets 16, 20 are arranged at the rear of the device, also to the right and to the left.

 Each secondary distribution cabinet 14 to 20 supplies a subgroup of functional members associated with it. These functional members are formed, for example, by electric actuators, or any other electrical apparatus.

 In FIG. 1, for each secondary distribution cabinet at 20, only four functional members are shown. They are designated by the same reference number as the cabinet with which they are associated, followed by the letters A, B, C or D.

 In practice, in some aircraft, around fifty functional units are associated with each secondary distribution cabinet.

 The secondary distribution cabinets 14 to 20 are each connected to the main distribution cabinet 12 by a power cable 22, 24, 26 and 28. Each power cable 22 to 28 is common to all of the functional members associated with The secondary distribution cabinet supplied by the power cable.

 As shown in FIG. 2 representing for example the cabinet 14, each secondary distribution cabinet includes a printed circuit 30 on which an electromechanical protection member is installed for each functional member connected to the cabinet. Each protection member is advantageously formed by an electromechanical circuit breaker. The circuit breakers, denoted 36, 38 and 40 in FIG. 2, each comprise two power connection terminals denoted respectively 36A, 36B, 38A, 38B and 40A, 40B. These terminals provide their electrical connection to power tracks on the printed circuit.

 A power track ensuring the main supply of the printed circuit 30 is electrically connected to the associated power cable 22.

This connection is effected by means of a tab 42 fixed to the end of the power cable 22. It is electrically connected to the track of the printed circuit 30 by a bolt 44 or any other suitable connection device.

 A terminal of each circuit breaker is connected, by a power track independent of the printed circuit, to a pin of a connector 46 for supplying the functional members. The other terminal of the circuit breaker is connected to the main power supply track of the printed circuit.

 The structure of the printed circuit 30 will be described in detail in the following description.

 As shown in FIG. 1, the functional members are returned to the supply connector 46 by a bundle 48 of wires including, for each functional member, a clean supply conductor connecting the functional member to the corresponding pin of the connector 46.

 The harness 48 has at its end a connector adapted to snap onto the power connector 46.

 Circuit breakers 36 to 40 have, each opposite the connection terminals, a reset button 36C, 38C, 40C protruding from! to a wall 50 delimiting the front face of the secondary cabinet.

 They are distributed, as shown in Figure 1, in rows and columns on the entire front of the secondary cabinet!

 Each circuit breaker has an auxiliary status contact for electrically detecting the on or open state of the circuit breaker. The auxiliary status contacts of the circuit breakers are connected to the circuit status control tracks of the circuit board by circuit breaker status control terminals denoted, respectively, 36D, 36E, 38D, 38E, 40D, 40E in FIG. 2 .

 The state control tracks to which the circuit breaker status contacts are connected are each connected to a management circuit 52 which is fixed parallel to the printed circuit 30. The management circuit 52 carries a printed circuit on which the components are installed intended for managing the control of circuit breaker states.

 This circuit 52 is connected by conductors 54 to the state control tracks of circuit 30. The circuit 52 comprises a connector 56 to which is connected, for each secondary cabinet, a bundle of control conductors 62, 64, 66, 68, connecting the status contacts to a switchboard 70 located in the cockpit of the aircraft. This table includes displays ensuring the availability of circuit breaker status to the crew.

 In order to know the state of the circuit breakers, the state control tracks of the printed circuit associated with the state contacts are supplied successively one after the other, in order to know by scanning the state of each of the circuit breakers.

 To ensure decoupling of rows and columns, each circuit breaker is provided with a diode.

 Electromechanical circuit breakers have a rating between 1 and 15 Amps.

 By way of example, the circuit breaker 36 is shown in perspective in FIG. 3.

 In this figure, the two power connection terminals 36A and 36B appear and the two state control terminals 36D, 36E.

 These four terminals are carried by a rear face of the parallelepipedic case of the circuit breaker.

 The circuit breaker housing is of means 80 for mechanically fixing the circuit breaker to the printed circuit 30.

 These means 80 comprise a strap 82 overlapping the case of the circuit breaker. This strap has, in section, the shape of a U. It extends along two opposite lateral faces of the housing and on its upper face carrying the reset button 36C.

 The strap is provided at each end with two connecting lugs 84 adapted to be received in holes in the printed circuit. They are each intended to be welded to a metal patch thereof.

 As illustrated in FIG. 4, the printed circuit is advantageously a multilayer circuit. In the example shown, it has six layers.

 The upper layer, denoted 100, in contact with the circuit breaker boxes constitutes a supply layer. This defines the main supply track 100A to which a first tab 36A, 38A, 40A of each circuit breaker is connected. The thickness of track 100A is at least 150 μm.

 Below the supply layer 100 are arranged two superposed distribution layers denoted 102 and 104. These carry power tracks 102A, 104A connecting the terminals 36B, 38B, 40B of the circuit breakers to the corresponding terminals of the connector. food 46.

The thickness of the power tracks 102A and 104A is greater than 150 μm.

 Below the distribution layers 102 and 104 are provided two monitoring layers 106, 108 delimiting the state control tracks 106A, 108A intended for the connection of the state control terminals 36D, 36E, 38D, 38E, 40D, 40E circuit breakers.

 The thickness of the control tracks is of the order of 35 μm.

 These tracks connect the state control terminals to the management circuit 52.

 Finally, the printed circuit 30 comprises a lower thermal drainage layer 110, the metal track 110A of which has a minimum thickness of 150 μm. This track is intended to evacuate the heat to a heat sink.

 As known per se, the different layers of the printed circuit are joined to each other to form a plate. Lights are provided in the different layers of circuit 30 in order to allow connection of the terminals of the circuit breakers and connectors with the associated tracks of one or the other of the layers.

 The use of such a printed circuit reduces the number of wired connections to be made, which reduces the mounting cost and the weight of the network.

Claims (8)

 1.-Cabinet (14, 16,18,20) for the secondary distribution of electrical power of an aircraft, of the type comprising electromechanical protection members (36,38,40), intended to be installed in a supply network electric of an airplane between a main power distribution cabinet (12) and functional components (14A, 14B, 14C, 14D, 16A, 16B, 16C, 16D, 18A, 18B, 18C, 18D, 20A, 20B, 20C , 20D) of the aircraft, characterized in that it comprises a printed circuit on which the protection members (36, 38, 40) are located, which circuit includes power tracks (100A, 102A, 104A) to which are connected the protection members, and in that it includes means (44,46) for electrical connection of the power tracks, on the one hand, to a power cable (22, 24,26,28) from the 'cabinet (12) main power distribution and, on the other hand, to each of the protected functional organs.  2.-cabinet according to claim 1, characterized in that each electromechanical protection member is a circuit breaker.  3. Cabinet according to claim 1 or 2, characterized in that each protection member has terminals (36A, 36B, 38A, 38B, 40A, 40B) for electrical connection to the power tracks of the printed circuit (30), and in that there are provided means (80) for mechanical fixing of each protection member to the printed circuit (30), which mechanical fixing means (80) are independent of the electrical connection terminals (36A, 36B, 38A , 38B, 40A, 40B).  4. Cabinet according to claim 3, characterized in that said mechanical fixing means (80) comprise a strap (82) overlapping each protection member, which strap (82) has, at its ends, on either side of the protection member, of the tabs (84) for mechanical connection to the printed circuit (30).  5. Cabinet according to any one of the preceding claims, characterized in that each protection member comprises a state contact, representative of the state of the protection member, and the printed circuit (30) comprises tracks control state (106A, 108A) to which said state contacts are electrically connected, the printed circuit (30) comprising means (56) for connecting the state control tracks to setting means (70) at the disposal of the state of the protection bodies.  6. Cabinet according to claim 5, characterized in that the printed circuit (30) is a multilayer printed circuit, at least one layer (100, 102,104) carrying only power tracks (100A, 102A, 104A) and at least a layer (106,108) carrying only state control tracks (106A, 108A).  7. Cabinet according to any one of the preceding claims, characterized in that the printed circuit (30) is a multilayer circuit, at least one layer (100) carrying power tracks (100A) for the connection of a cable. of power (22,24,26,28) to the protection members (36, 38,40) and at least one layer (102,104) carrying power tracks (102A, 104A) for the connection of the protection members (36, 38.40) to the protected functional organs.  8.-cabinet according to claim 6 or 7, characterized in that the printed circuit comprises a thermal drainage layer (110).