System and method for electrically and mechanically coupling an avionics line replaceable unit with electronic equipment

[0002] The present application is related to co-pending patent application entitled System And Method For Electrically Coupling An Avionics Line Replaceable Unit With An Avionics Test Station filed on even date herewith by the same inventor and assigned to the same assignee. This application is incorporated herein in its entirety by this reference.

[0003] The present invention generally relates to aviation electronics or avionics, and more particularly relates to line replaceable units (LRUs) of avionics equipment which are mated to a rack and/or mounting tray in an aircraft, and even more particularly relates to a system and method for electrically and mechanically coupling such LRUs with other electronic equipment.

[0004] In the past, designers of avionics systems have endeavored to provide systems with improved reliability and improved serviceability. One crucial element in such systems has been the use of line replaceable units which can be quickly removed from the aircraft upon any failure or for routine maintenance. These line replaceable units may be replaced with a spare line replaceable unit or tested on a test station and repaired. These test stations are typically very versatile, being capable of testing various different types of avionics equipment. The versatility of these test stations arises out of the use of various test unit adapters (TUAs), which are tailored to electrically connect various avionics LRUs with the test station.

[0005] While these line replaceable units, test stations and TUAs have many advantages, they also have significant drawbacks.

[0006] First of all, these line replaceable units are usually blind mated with connectors in an avionics rack on the aircraft or with the TUAs. When these line replaceable units are mated with such connectors, the connectors typically provide both electrical and mechanical coupling. In fact, due to positional tolerance issues, the line replaceable units are held suspended only by these connectors. This required misalignment and subsequent suspension of line replaceable units results in undesirable stress and strain being placed upon the electrical connection contacts.

[0007] Secondly, when the line replaceable units are mated to a TUA in a test station (which have generally much larger tolerances than airborne avionics equipment) the amount of uncertainty of alignment increases, thereby increasing the likelihood of pin damage resulting from improper alignment upon mating.

[0008] Consequently, there exists a need for improvement in avionics systems and methods for coupling LRUs to such systems.

[0009] It is an object of the present invention to provide enhanced reliability for avionics LRUs.

[0010] It is a feature of the present invention to utilize an LRU with a floatable connector interface.

[0011] It is an advantage of the present invention to allow the LRU to be mated without a suspended alignment approach to the connector.

[0012] It is another advantage of the present invention to decrease the potential for pin damage upon insertion.

[0013] The present invention is an apparatus and method for mating avionics LRUs with other electronic equipment, which is designed to satisfy the aforementioned needs, provide the previously stated objects, include the above-listed features and achieve the already articulated advantages. The present invention is carried out with a “suspension-less LRU” in a sense that the amount of mechanical suspension by the connector has been greatly reduced.

[0014] Accordingly, the present invention is a system and method for mating avionics LRUs with other electronic equipment where the system includes a floatable electrical connector, and the method includes placing the LRU on a rest, sliding it into position without raising the LRU above the rest.

[0015] The invention may be more fully understood by reading the following description of the preferred embodiments of the invention, in conjunction with the appended drawings wherein:

[0016] FIG. 1 is a simplified exploded diagram of a system and environment of the prior art, where the dotted and dashed lines show the orientation of objects when in an assembled state.

[0017] FIG. 2 is a perspective view of an LRU side of a TUA having a floating connector.

[0018] FIG. 3 is an exploded perspective view of an LRU side of a TUA, where the dotted and dashed lines show the orientation of objects when in an assembled state.

[0019] FIG. 4 is an enlarged perspective view of an opposite side of an LRU side of a TUA of FIG. 2.

[0020] FIG. 5 is an enlarged and exploded perspective view of an encircled area of FIG. 3.

[0021] Now referring to the drawings, wherein like numerals refer to like matter throughout, and more particularly to FIG. 1, there is shown a system of the prior art, generally designated 100, which includes in an aircraft 102, an on-board avionics rack 104, with several avionics line replaceable units 106 disposed therein. On-board avionics rack or mounting tray 104 is shown having an unoccupied slot 108 therein with an on-board rack mounted rack/LRU connector interface 109 disposed at its inside end. Non-installed avionics line replaceable unit 112 is shown removed from unoccupied slot 108 and is shown having an avionics line replaceable unit rear blind mating connector interface 119 for coupling with on-board rack mounted rack/LRU connector 109. On-board rack mounted rack/LRU connector 109 and avionics line replaceable unit rear blind mating connector interface 119 are often, but are not necessarily, of a standardized design set by aviation standard setting body ARINC. Also shown in FIG. 1 is hand-wired TUA 122 having a TUA/LRU connector 124, a TUA/test station connector interface 129 and hand-wired interconnection wires 126 disposed therebetween. Hand-wired TUA 122 is shown as removed from one of two TUA docking stations 132 of test station 130. Each TUA docking station 132 has a test station/TUA connector interface 134 therein for coupling with TUA/test station connector interface 129 of hand-wired TUA 122. TUA/LRU connector 124 may be of similar or identical design to on-board rack mounted rack/LRU connector 109 and consequently, TUA/LRU connector 124 is capable of receiving avionics line replaceable unit rear blind mating connector interface 119 of non-installed avionics line replaceable unit 112.

[0022] Now referring to FIG. 2, there is shown a perspective view of the TUA 2220, having docking station locking pins 2222, test station side 2224, TUA handle 2225, and LRU front 2226. TUA 2220 also shows an avionics line replaceable unit TUA/LRU connector 124 disposed on floating connector plate 2227 on LRU front 2226. Shown on floating connector plate 2227 is a floating connector plate alignment hole 2228. Avionics line replaceable unit TUA/LRU connector 124 may be an ARINC connector or any other type of multi-pin connector which can perform the necessary interface functions.

[0023] Now referring to FIG. 3, there is shown an exploded perspective view of portions of the present invention, including a first Teflon isolator 302 (shown exploded) attached to LRU front 2226 and a second Teflon isolator (not shown) is attached to floating connector plate 2227. Also shown is a first vertical axis race assembly 310 for coupling with floating connector plate 2227 to provide an axis link to LRU front 2226. First vertical axis race assembly 310 includes a first top station spring 312, a first vertical axis controlling bracket 314, and a first bottom station spring 316 all disposed along a first vertical bearing race 319. First vertical axis controlling bracket 314 in combination with a first stop retainer 318 is provided to limit the horizontal and rotational float of first vertical axis race assembly 310. A second vertical axis race assembly 320, which may be preferably similar or identical to first vertical axis race assembly 310 in function and construction, is also shown. Second vertical axis race assembly 320 includes a second top station spring 322, a second vertical axis controlling bracket 324 and a second bottom station spring 326, as well as a second stop retainer 328 and a second vertical bearing race 329

[0024] TUA/LRU connector 124 is coupled to floating connector plate 2227 through top and bottom mounting flanges 304 and 306 respectively.

[0025] Now referring to FIG. 4, there is shown additional portions of the present invention, including top horizontal axis assembly 410 and horizontal axis assembly 420, which provides and controls horizontal float of the avionics line replaceable unit TUA/LRU connector 124. Top horizontal axis assembly 410 includes first top vertical float stop 412, first top station spring 414, top horizontal race 416, second top station spring 418 and second top vertical float stop 419. Top horizontal race 416 extends through first vertical axis race assembly 310 and second vertical axis race assembly 320. In a similar fashion, there is shown bottom horizontal axis assembly 420, which includes first bottom vertical float stop 422, first bottom station spring 424, bottom horizontal race 426, second bottom station spring 428, and second bottom vertical float stop 429.

[0026] Now referring to FIG. 5, there is shown an enlarged exploded perspective view of portions of first vertical axis race assembly 310 shown in the encircled area of FIG. 3 labeled 5. A first vertical bearing race 319 is shown centrally disposed in first vertical axis race assembly 310. First vertical bearing race 319 may be similar or identical to second vertical bearing race 329. Disposed about first vertical bearing race 319 is top linear bearing 502 and bottom linear bearing 504.

[0027] In operation, an avionics line replaceable unit TUA/LRU connector 124 can be floatably mounted to an on-board avionics rack 104 or a TUA 2220 for receiving an avionics line replaceable unit 106 having an avionics line replaceable unit rear blind mating connector interface 119 thereon. The floatability of TUA/LRU connector 124 allows for many benefits. First of all, an LRU can be placed in an on-board avionics rack 104 or test station 130 and slid into place. As the avionics line replaceable unit rear blind mating connector interface 119 meets with the TUA/LRU connector 124, the TUA/LRU connector 124 is allowed to float to a new position, preferably sufficiently low enough so that the LRU can be mated without raising the LRU off the rest. This reduces stress and strain upon the contacts in avionics line replaceable unit rear blind mating connector interface 119 and/or TUA/LRU connector 124. Preferably the float of the TUA/LRU connector 124 is in at least two directions and has sufficient float to accommodate the potential misalignment of avionics line replaceable unit rear blind mating connector interface 119 and TUA/LRU connector 124. Often the tolerances for TUA/test station combinations are higher than tolerances for LRUs. When this is the case, the potential amount of misalignment is greater. An alignment shaft may be attached to the LRU, or more preferably to a receiving apparatus used on the test station 130. This alignment shaft cooperates with floating connector plate alignment hole 2228 to pre-align the avionics line replaceable unit rear blind mating connector interface 119 and the 124 to accommodate for these higher tolerances. Preferably, the floatability of TUA/LRU connector 124 allows for mating without a requirement to raise the LRU off the rest and, therefore, without the need to mechanically suspend the LRU by the avionics line replaceable unit rear blind mating connector interface 119 and TUA/LRU connector 124 combination.

[0028] Horizontal float and float limitation are accomplished by top horizontal axis assembly 410 and horizontal axis assembly 420 which permits a horizontal translation of first vertical axis race assembly 310 and second vertical axis race assembly 320 along top horizontal race 416. Horizontal float is limited by first vertical axis controlling bracket 314 and second vertical axis controlling bracket 324 in cooperation with second vertical float stop bracket 328 and first vertical float stop bracket 318 determined by their relative feature of size allocations.

[0029] Vertical float and float limitation are accomplished by first vertical axis race assembly 310 and second vertical axis race assembly 320 which permit vertical translation of top horizontal axis assembly 410 and horizontal axis assembly 420 along first vertical bearing race 319 and second vertical bearing race 329. Vertical float is limited by first top vertical float stop 412 and second top vertical float stop 419, as well as first bottom vertical float stop 422 and second bottom horizontal float stop 429.

[0030] Rotational float and float limitation are accomplished by rounding ends of top horizontal race 416, and bottom horizontal race 426 and the features of size correlation of first vertical axis controlling bracket 314 to first vertical float stop bracket 318 and second vertical axis controlling bracket 324 to second vertical float stop bracket 328.

[0031] It is thought that the method and apparatus of the present invention will be understood from the foregoing description, and that it will be apparent that various changes may be made in the form, construct steps and arrangement of the parts and steps thereof, without departing from the spirit and scope of the invention or sacrificing all of their material advantages. The form herein described is merely a preferred exemplary embodiment thereof.