GB2463867A

GB2463867A - An electrical harness

Info

Publication number: GB2463867A
Application number: GB0817479A
Authority: GB
Inventors: Jonathan Wilson; Keith Dempsey
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2008-09-24
Filing date: 2008-09-24
Publication date: 2010-03-31
Also published as: GB0817479D0

Abstract

An electrical harness, for example for a gas turbine engine, comprises a printed circuit board 44 which is provided with at least one connector component 58. Each connector component comprises a housing which receives a region 70 of the printed circuit board and at least one connection element 78 which may take the form of a pin press fitted into a conductive hole in the printed circuit board. The connection element 78 extends in a direction inclined, preferably perpendicularly, to the plane of the region 70 of the printed circuit board disposed in the housing. The housing may comprise of a body 64 and lid 66; the body 64 may have a first recess 74 for accommodating the contact terminals 78 and a second recess 76 extending laterally of the first to accommodate the circuit board. The printed circuit board is preferably a flexible printed circuit board which constitutes the entire wiring harness and in this way can provide a flexible and compact wiring harness.

Description

AN ELECTRICAL HARNESS

This invention relates to an electrical harness and is particularly, although not exclusively, concerned with an electrical harness for a gas turbine engine.

A typical gas turbine engine has a substantial number of electrical components which serve, for example, to sense operating parameters of the engine and to control actuators which operate devices in the engine. Such devices may, for example, control fuel flow, variable vanes and air bleed valves. The actuators may themselves be electrically powered, although some may be pneumatically or hydraulically powered, but controlled by electrical signals.

Electrical power, and signals to and from the individual electrical components, are commonly transmitted along conductors in the form of wires and cables which are assembled together in a harness. Connections between the individual components and the harness are made, for example, by multi-pin plug and socket connectors. Similarly, communication between the harness and power, control and signalling circuitry is achieved through a multi-pin connector.

By way of example, Figure 1 of the accompanying drawings shows a typical gas turbine engine including two wiring harnesses 2, 4, each provided with a respective connector component 6, 8 for connection to circuitry accommodated within the airframe of an aircraft in which the engine is installed.

The harnesses 2, 4 are assembled from individual wires and cables which are held together over at least part of their lengths by suitable sleeving or braiding. Individual wires and cables, for example those indicated at 10, emerge from the sleeving or braiding to terminate at plug or socket connector components 1 2 for cooperation with complementary socket or plug connector components 14 on, or connected to, the respective electrical components.

Figure 2 of the accompanying drawings shows a typical connector component in the form of a socket 12 at the end of a cable 10, fitted to a complementary plug 14.

The cable 1 0 is a screened cable having an external conductive screen 1 6 enclosing conductors 18 which are individually screened by braided screens 20. The individual conductors 18 are connected to respective pins 22 which are supported parallel to each other in a backshell 24 for engagement with respective hollow conductors of the plug 14.

The external screen 16 and the individual screens 20 are electrically connected to the backshell 24 by means of a crimped fitting 25, and a protective boot 26 extends over the backshell 24, the fitting 25 and the end region of the cable 10.

It will be appreciated from Figure 2 that the socket 1 2 is relatively long in the insertion direction of the plug. This arises because a significant amount of space is needed to terminate the individual conductors 1 8 into crimped buckets in the pins 22. Even if the boot 26 is formed to direct the cable 1 0 laterally of the insertion direction, a significant amount of space is needed to accommodate the socket and to enable it to be engaged to and disengaged from the plug 14. Furthermore, the bundles of wires and cables in the harnesses 2, 4 are relatively bulky and resistant to flexure, and are not suited to routing on the external geometry of a gas turbine engine.

According to the present invention there is provided an electrical harness of which at least part comprises a printed circuit board provided with a connector component, the connector component comprising a housing, into which the printed circuit board extends, and at least one connection element which is carried by the printed circuit board in electrical contact with a conductive region of the printed circuit board, and which extends in a direction inclined to the plane of the region of the printed circuit board disposed within the housing.

By using an electrical harness in accordance with the present invention, it is possible to construct the connector component so that it has a relatively small dimension in the connection direction, so that the connector as a whole has a relatively small space requirement.

The printed circuit board may be flexible over at least part of its extent, to enable it to be routed over the external geometry of an assembly, such as a gas turbine engine, on which it is installed.

The region of the printed circuit board disposed within the housing may have a hole which extends through the conductive region and receives the connection element, for example as a press fit. The conductive region may include a conductive layer provided on the wall of the hole.

The housing may have a first recess into which the connection element extends from the printed circuit board for engagement with further connection elements of a complementary connector component, and a second recess extending laterally of the first recess, in which is located the region of the printed circuit board disposed within the housing. The housing may comprise a body defining the first and second recesses and a lid for retaining, in the second recess, the region of the printed circuit board disposed within the housing.

The connection element may be one of a plurality of connection elements of the housing, each connection element being in electrical contact with a respective conductive region of the printed circuit board. The connector component may be one of a plurality of connector components of the electrical harness, each connector component receiving a respective region of the printed circuit board.

The printed circuit board may constitute substantially the entire electrical harness.

The present invention also provides a gas turbine engine having a plurality of electrical devices which are electrically connected to further circuitry, such as a source of electrical power, a signal input or a signal output, by an electrical harness as defined above, the or each connector component of the harness being coupled to a complementary connector component of the respective electrical device.

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figures 1 and 2, as discussed above, show a typical known gas turbine engine and a typical known electrical connector; Figure 3 shows a gas turbine engine provided with an electrical harness in accordance with the present invention; Figure 4 is a diagrammatic representation of an electrical harness for the engine of Figure 3; Figure 5 shows a connector of the engine of Figure 3; Figure 6 is an exploded view of the connector of Figure 5; and Figure 7 is an enlarged view of part of the connector of Figures 5 and 6.

In the engine shown in Figure 3, the harnesses 2, 4 of the engine of Figure 1 have been replaced by harnesses 32, 34 which each consists, substantially entirely, of a flexible hybrid printed circuit board. Thus, as shown in Figure 4, the harness 32 may comprise a trunk 36 extending between connector components 40, 42, and a plurality of integral spurs 44 terminating at connector components 46.

The trunk 36 and spurs 44 are generally flat, parallel to the plane of Figure 4, but may be curved in that plane for ease of routing of the harness over the gas turbine engine.

The material of the printed circuit board is flexible, so that the harness 32 may be flexed out of the plane of Figure 4. The dielectric material of the printed circuit board is provided with conductive regions in the form of tracks extending over the surface of the dielectric material, at least some of which tracks extend both along the trunk 36 and the respective spurs 44. It will be appreciated that the widths of the spurs 44 and of the trunk 36 will vary from one another in dependence on the nature and density of the conductors which they carry.

The connector components 40, 42 and 46 have the general form represented by a socket 58 in Figures 5 to 7. In practice, the connector components will have different specifications according to the function they have to perform. It will be appreciated that some aspects of the connector components will be defined by appropriate recognised standards. The socket 58 engages a plug 60. The socket 58 comprises a housing 62, made up of a body 64 and a lid 66. As shown in Figures 5 and 6, a region 70 of the part of the printed circuit board forming one of the spurs 44 is disposed within the housing 62. Thus, while the majority of the flexible printed circuit board forming the harness 32 is situated outside the housing 62, the spur 44 projects into the housing 62 through a "letterbox" opening 72 defined between the body 64 and the lid 66.

The body 64 comprises a first recess 74 which is generally cylindrical, and a second recess 76 which extends laterally from the first recess 74 and accommodates the region 70 of the spur 44.

An array of terminal pins 78 is mounted on the region 70 of the spur 44. The pins 78 are a press fit in holes 80 in the spur 44, and each has an enlarged head 82 to locate it in the correct lengthwise position. Each pin 78 passes through a respective conductive track on the spur 44 so that it is in electrical contact with that track. In order to assist this, the conductive material of the respective track on the spur 44 extends over the internal wall of the hole 80.

The region 70 of the spur 44 is then placed in the second recess 76, so that the pins 78 project into the first recess 74 and are presented for engagement with a complementary array of hollow terminal elements (not shown) in the plug 60. The heads 82 of the pins 78 are overlaid by a compliance layer 84 to damp out any vibration that may arise in any of the components. Finally, the lid 66 is placed over the second recess 76 where it is permanently or removably secured to housing 62 in order to enclose the end of the spur 44. The body 64 may also be provided with suitable mechanical attachment features for engagement with, and securing to the region 70 of the spur 44.

The harness 32 may be a flexible hybrid printed circuit board, provided with both signal and power conductive tracks. The printed circuit board is preferably screened, with suitable screen terminations made within the body 64. The connector 58 is also provided with suitable mechanical attachment features for engagement with, and securing to, the plug component 60.

It will be appreciated from Figure 3 that the use of a harness of the form shown in Figure 4, with connector components as shown in Figures 5 to 7 enables a significant reduction in the space required in the region of the connectors and also assists in the routing of the harnesses 32, 34 around the engine exterior. Furthermore, the socket 58 may be reduced in complexity, weight, cost and volume. In Figures 5 to 7, the pins are shown perpendicular to the plane of the region 70 of the printed circuit board, so that the spur 44 emerges from the opening 72 in a direction perpendicular to the insertion direction of the socket 58. However, other lead out angles for the spur 44 are possible to suit the local geometry of the engine.

In an alternative embodiment, the terminal pins 78 are inserted into the holes 80 in the opposite direction from that shown in Figures 5 to 7, in other words from the side facing the plug 60 in use. In that embodiment, the head 82 would be replaced by a shoulder situated away from the end of the pin 78. Also, the pins 78 could be soldered to the printed circuit board to increase robustness and ensure a sound electrical connection.

The pins 78 could be replaced by hollow sockets for engagement by pins in the complementary component 60.

It will be appreciated that means for relieving strain can be provided in the region of the opening 72, either on the housing 62 or on the adjacent region of the printed circuit board.

Claims

CLAIMS1 An electrical harness (32, 34) of which at least part comprises a printed circuit board provided with a connector component (58), the connector component (58) comprising a housing (62) into which the printed circuit board extends, and at least one connection element (78) which is carried by the printed circuit board in electrical contact with a conductive region of the printed circuit board, and which extends in a direction inclined to the plane of the region (70) of the printed circuit board disposed within the housing (62).
2 An electrical harness as claimed in claim 1, characterised in that the printed circuit board is flexible.
3 An electrical harness as claimed in claim 1 or 2, characterised in that the connection element (78) is in the form of a pin, and the region (70) of the printed circuit board disposed within the housing (62) has a hole (80) which extends through the conductive region and which receives the connection element (78).
4 An electrical harness as claimed in claim 3, characterised in that the connection element (78) is a press fit in the hole (80).
An electrical harness as claimed in claim 3 or 4, characterised in that the conductive region extends over the inner wall of the hole (80).
6 An electrical harness as claimed in any one of the preceding claims, characterised in that the connection element (78) extends perpendicular to the plane of the region (70) of the printed circuit board disposed within the housing (62).
7 An electrical harness as claimed in any one of the preceding claims, characterised in that the housing (62) has a first recess (74) into which the connection element (78) extends from the printed circuit board for engagement with a further connection element of a complementary connector component (60), and a second recess (76) extending laterally of the first recess (74), in which is located the region (70) of the printed circuit board disposed within the housing (62).
8 An electrical harness as claimed in claim 7, characterised in that the housing (62) comprises a body (64) defining the first and second recesses (74, 76) and a lid (66) for retaining within the second recess (76) the region (70) of the printed circuit board disposed within the housing (62).
9 An electrical harness as claimed in any one of the preceding claims, in which the connection element (78) is one of a plurality of connection elements, each of which is in electrical contact with a respective conductive region of the printed circuit board.
1 0 An electrical harness as claimed in any one of the preceding claims, characterised in that the connector component (58) is one of a plurality of connector components (40, 42, 46), each of which receives a respective region (70) of the printed circuit board.
11 An electrical harness as claimed in any one of the preceding claims, characterised in that the printed circuit board constitutes substantially the entire harness.
1 2 A gas turbine engine having a plurality of electrical devices electrically connected to further circuitry by an electrical harness (32, 34) in accordance with any one of the preceding claims, the or each connector component (40, 42, 46) of the harness being coupled to a complementary connector component (60) of the respective electrical device.
1 3 An electrical harness substantially as hereinbefore described and/or with reference to figures 3 to 7 of the accompanying drawings.
14 A gas turbine engine substantially as hereinbefore described and/or with reference to figures 3 to 7 of the accompanying drawings.