Electrical distribution system and modular high power board contactor therefor

An electrical distribution system provides a Line Replaceable Modules (LRM) with a printed wire board (PWB) which is of a relatively thick construction. The PWB is manufactured of a relatively thick construction to provide structural support for a multitude of electrical components as well as a board mounted contactor. Each contactor is mounted directly to the PWB. As the primary contactor switch function is board mounted, support functions such as coil drivers, economizing switches, auxiliary switches become PWB mounted components that are assembled to the PWB for communication through the board circuit traces rather than the heretofore required wiring harnesses.

BACKGROUND OF THE INVENTION

The present invention relates to an electrical energy distribution systems, and more particularly to a board mounted contactor therefor.

Electrical energy distribution systems typically include an electrical power source which powers a corresponding distribution circuit through a controllable power contactor which selectively interlinks a multitude of distribution circuits. Each distribution circuit is powered by its own source through a corresponding power contactor, however, should a source become defective, the distribution circuit can be powered by the source of at least one other distribution circuit through at least one contactor.

Distribution systems of this type are often utilized onboard aircraft. In this environment, each distribution circuit generally powers a distribution bus bar which then powers a plurality of electrical loads in parallel. Each power source is typically either of a generator driven by an engine of the aircraft, an auxiliary power unit or batteries.

The contactors reside in a power center assembly on a primary bus bar structure located within an aircraft electronics bay. The primary bus bars interface to the contactors through 6 threaded terminal posts, assuming it is a 3 phase, AC contactor. In addition to the primary power interfaces, a low power signal connection is required for control and sensing functions. Because the contactors are line replaceable modules (LRMs) each contactor must have an individual chassis to support a multitude of electrical components and wiring harnesses which connect the LRM to the power center assembly.

The contactors each include an economizer switch to reduce coil currents once closure occurs and a multitude of auxiliary contact switches which indicate the main contact position and who's signals are used for relay logic in the power system. Each of these auxiliary switches are mechanically linked to the contactors primary actuator through a complex set of brackets and adjustment screws. In addition, each of the switches requires a harness to provide the interface to the control and signal connector. During LRM replacement, tooling is required to remove the control and signal connector and large tooling is required to remove fasteners on the primary power interfaces. These interfaces also require a controlled re-torquing procedure and calibrated torque wrench during LRM replacement. Although effective, these features result in a relatively complex LRM that reduces reliability and may result in increased maintenance considerations when located within an aircraft environment.

Accordingly, it is desirable to provide an uncomplicated line replaceable module with a minimum of wire harness connections which reduces maintenance considerations when located within an aircraft environment.

SUMMARY OF THE INVENTION

A electrical distribution system according to the present invention includes a Line Replaceable Module (LRM) with a printed wire board (PWB) which is of a relatively thick construction. The PWB is of a relatively thick construction to provide structural support for a multitude of electrical components as well as a board mounted contactor.

The PWB supports and electrically interconnects the contactors, power interface connectors, auxiliary switches, current sensors, control interface connectors, and an onboard controller. The board mounted power interface connectors communicate power from a primary power distributing bus bar, to respective contactors through board mounted bus structure. The PWB mounted contactors also distribute power to other PWB mounted components through circuit traces formed onto the PWB.

Each contactor is mounted directly to the PWB and is simplified. The contactor consists of the primary motor which actuates the three primary power contacts and one position switch on the end of the contactors actuation stem. This simplification is possible as the support functions such as coil drivers, economizing switches, and auxiliary switches are PWB mounted components that communicate through the board circuit traces rather than the heretofore required wiring harnesses, mechanical switches and support brackets The system can now be supported with as many logic signals as needed without further mechanical interfaces on the contactor. The contactor LRU chassis is reduced or removed with only one position switch to protect.

The present invention therefore provides an uncomplicated line replaceable module with a minimum of wire harness connections, improved reliability and reduced maintenance considerations when located within an aircraft environment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1A and 1Billustrate a general schematic view of an electrical distribution system10preferably for use with an aircraft. It should be understood that the present invention is not limited to just aircraft environments as various vehicles and stationary emplacements which utilize a multitude of power sources will benefit from the present invention.

The system10generally includes a multiple of primary power distributing bus bars12which power a plurality of loads which are primary power distributing Line Replaceable Modules (LRMs)14. The LRMs14disclosed herein are primary power panels which communicate power on the order of hundreds of amps. From the LRMs14, power is distributed to secondary bus bars (FIG. 1A) for distribution to vehicle subsystems at the desired power level typically on the order of tens of amps. Each power distributing bus bar12is powered by electrical energy generated from one of a multitude of electrical power source16such as a generator, driven by an engine of the aircraft, an auxiliary power unit APU or batteries.

Each LRM14includes an interconnection contactor20which is selectively controlled such that power may be received from one of a multiple of the sources16. That is, the LRM14mounts the contactor20directly to a printed wire board (PWB)22of the LRM14rather than to the primary bus structure on the primary distribution assembly. Each PWB22includes a multiple of contactors20. Each contactor communicates power from one source16to the LRM14.

Referring toFIG. 2, each of the LRMs14are mounted within a chassis24which includes the power distributing bus bar12typically located on an aft portion thereof. That is, the primary power distributing bus bar12is typically mounted to a chassis24such that the LRM14may be connected directly thereto. Preferably, the chassis24is mounted within a vehicle bay26(illustrated schematically) and the LRMs14are slid into the chassis24such that the contactors20are in communication with the respective bus bar12.

Referring toFIG. 3A, each LRM14preferably includes the PWB22which is of a relatively thick construction. The PWB22is manufactured of a relatively thick construction to provide structural support for a multitude of electrical components as well as the board mounted contactors20. The PWB22may be approximately 0.25 inches thick, however, it should be understood that various board thicknesses that provide the desired structure may be utilized with the present invention.

The PWB22generally supports and electrically interconnects the contactors20, power interface connectors28, auxiliary switches (mounted on the onboard controller board assembly)30, current sensors32, control interface connectors34, and an onboard controller36. The power interface connectors28(FIG. 3B) preferably include supply connections38which communicate power from the power distributing bus bar12(FIG. 1), to each of the contactors20which then distribute power to the other PWB22mounted components through a combination of bus and circuit traces40(illustrated schematically) formed onto the PWB22, depending on the current. The circuit traces40provide communication paths between the components as generally understood and transfer information such as the contactor20position sensed by the board mounted auxiliary switches30to a higher level controller (illustrated schematically at42) such as a flight controller through a control interface connectors35.

Referring toFIG. 4A, each contactor20is mounted directly to the PWB22. The contactor20may thereby be of a relatively straightforward construction in which the PWB22becomes the contactor20support structure. As the primary switch function is board mounted, support functions such as coil drivers, economizing switches, and auxiliary switches are also board mounted components that are assembled to the PWB22for communication through the circuit traces40rather than the heretofore required wiring harnesses.

Preferably, the contactor20includes a housing assembly46, a movable plunger48, and an actuator50such as a solenoid. The housing assembly46is preferably attached to the PWB22through fasteners f such as screws or the like (also illustrated inFIG. 4B). The power interface connectors28are also preferably attached adjacent an edge22E of the PWB22through fasteners f such as screws or the like (also illustrated inFIG. 4B). The power interface connectors28communicate electrical power to contacts52mounted to the contactor housing46though the supply connection38. Notably, only the relatively high power supply connection38which communicate power from the power interface connectors28to each of the contactors20do not utilize the circuit traces formed directly onto the PWB22. The power interface connectors28include a multiple of pins28P. The multiple of pins28P. in the disclosed non-limiting embodiment, include three pins28P on one side of the PWB22and a three pins below the PWB22. It should be understood that although the supply connections38are illustrated herein as separate from the PWB22, the supply connections38may alternatively be PWB22circuit traces. The contacts52are selectively closed by the plunger48which is driven by the actuator50. Preferably, the actuator50is mounted at least partially through the PWB22to minimize packaging volume of the LRM14(also illustrated inFIG. 3C). The actuator50communicates with the controller and receives power through the circuit traces40on the PWB22

The auxiliary switch30is preferably mounted adjacent to the plunger48(illustrated somewhat schematically) and within housing assembly46to detect movement of the plunger48. The auxiliary switch30communicates with the controller36through the circuit traces40on the PWB22.

As each of the auxiliary components which supports operation and position functions for the contactor20are mounted to the PWB22, communication with the controller36and the higher level controller42is readily facilitated. That is, the controller36preferably converts information from each of the board mounted auxiliary components to digital signals which may then be communicated to the higher level controller42and throughout the vehicle. The contactor20is thereby relatively uncomplicated since the only non-board mounted electrical communication path is preferably only that between the bus bar12and the contactor20. A rather elegant and uncomplicated power communication arrangement between the LRMs14and the bus bar12is thereby provided.

It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit from the instant invention.