Patent Application
20150332881
This invention relates, generally, to a differential motion sensor that may be employed with, for example, an actuation system of an aircraft and, more specifically, to an electromechanical fuse thereof.
A differential motion sensor, such as a slat disconnect sensor, uses an electromechanical fuse. The fuse is disposed between two arms of the sensor and carries a low voltage signal that, when interrupted, annunciates a fault to a controller of, for example, an actuation system of an aircraft. The sensor may be in communication with mechanical linkages (e.g., panels of a wing of the aircraft) designed to move together. Upon malfunction of one or more of these panels, the fuse fractures. Existing designs of the fuse define a small cross-section of the fuse, use steel or copper alloys as a conductor for the fuse, and have thin insulating coatings.
If tensile “fracture” load or strength of the fuse is too great, the fuse can drive an adjacent panel and not fracture. Due to normal handling of the sensor during manufacturing, assembly, and installation thereof onto the aircraft and/or thermal stresses of the fuse, insulation of the fuse according to existing designs is prone to such fracturing. More specifically, during such handling, the fuse may be subject to bending about “width” and “height” (thickness) directions thereof, which are primarily resisted by a height of the alloys and insulation in the “height” and “width” directions, respectively. As such, “bending” strengths of the fuse should be maximized to avoid damage thereto during the handling, and thickness of the insulation should be maximized as well to avoid “insulation” failures.
Also, in operation of the sensor, skew of a panel can occur such that the fuse is loaded in tension in a direction perpendicular to “height” and “width” directions of the fuse. Again, the tensile “fracture” strength of the fuse should be minimized to provide maximum sensitivity to such skew.
Accordingly, it is desirable for the tensile “fracture” strength of the fuse to be (maintained) low or minimized to add or even maximize sensitivity (including to panel skew) and reduce dormancy thereof. Yet, it is desirable also for the fuse to be sufficiently durable to survive manufacturing of the sensor and normal handling during assembly and installation thereof onto the aircraft. It is desirable also for the fuse to be (increasingly) resistant to handling, bending, and thermal stresses thereof and its insulation to be increasingly (maximally) thick to minimize “insulation” failures for a same low tensile “fracture” strength. It is desirable also for the fuse to maximize “bending” strengths thereof to avoid handling damage. Thus, it is desirable to provide a fuse of a differential motion sensor having improvements related to tensile “fracture” strength, sensitivity, dormancy, durability, bending and thermal-stress resistance, insulation thickness, and “bending” strengths of the fuse.
According to a non-limiting embodiment of the invention, an electromechanical fuse of a differential motion sensor is provided. The fuse includes at least one thick layer that acts as an insulating envelope of the fuse. A thin layer acts as a conductor of the fuse and is made of a lower-strength material.
The fuse is a conductive link over-molded with insulation. The link is made of a lower-strength conductive metal, which allows the fuse to possess a larger net section. Also, the fuse carries a low voltage signal, has a minimal tensile “fracture” strength, maximizes its sensitivity (including to panel skew) and “bending” strengths, reduces its dormancy, and is sufficiently durable and resistant to handling, bending and thermal stresses thereof. Furthermore, insulation of the fuse is maximally thick for greater durability while maintaining the same low tensile “fracture” strength. In addition, the fuse can be used in any differential-motion-sensing system. Moreover, the fuse can be used as a discriminator in a larger system since the fuse allows a more sensitive load to be employed, which reduces possibility of a dormant failure occurring.
The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawing in which:
Referring now to the figures, a non-limiting embodiment of an electromechanical fuse of a differential motion sensor according to the invention is shown at 20. Although the fuse 20 is disclosed herein as electromechanical, it should be appreciated that the fuse 20 can be any suitable type of fuse. Furthermore, although the fuse 20 is so disclosed as being implemented for a differential motion sensor of an actuation system of an aircraft, it should be appreciated also that the fuse 20 can be implemented for any suitable differential-motion-sensing system or even any suitable type of sensor.
Referring now specifically to
More specifically, the panels are designed to move together, synchronized in time, during normal operation of the panels (i.e., the panels are configured to move “in sync” with respect to each other). The panels can be wing slats or any two panels designed to move in sync with respect to each other. In a case in which the panels are slats, the panels are generally configured to move in forward and aft directions. If the panels become disconnected from each other, there is relative motion between the panels such that the pin 22 strikes one of the arms 12, 14. In this way, the fuse 20 is loaded, causing fracture of the fuse 20 and detection of the fracture of the panel skew. One of the panels includes a pin 22 that extends into a space defined between the arms 12, 14 and is fixed to the panel. The sensor 10 is fixed to the other panel.
Referring now specifically to
The frame 24 defines also a thin middle layer 28 that is sandwiched between the insulating layers 26 and acts as the conductor 28. The conductive layer 28 is made of a lower-strength material, such as metal. In an aspect of the non-limiting embodiment, the fuse 20 uses aluminum alloy 1060, H12 as the conductor 28. However it should be appreciated by those having ordinary skill in the related art that the fuse 20 can use any suitable lower-strength conductive material, in general, and metal, in particular, as the conductor 28—such as tin, lead, zinc-based alloys, and other lower-strength conductive metals.
Referring now specifically to
Referring now specifically to
The fuse 20 is a conductive link overmolded with insulation. The link is made of a lower-strength conductive material, which allows the fuse 20 to possess a larger net section. Also, the fuse 20 carries a low voltage signal, has a minimal tensile “fracture” strength, maximizes its sensitivity (including to panel skew) and “bending” strengths, reduces its dormancy, and is sufficiently durable and resistant to handling, bending and thermal stresses thereof. Furthermore, insulation of the fuse 20 is maximally thick for greater durability while maintaining the same low tensile “fracture” strength. In addition, the fuse 20 can be used in any differential-motion-sensing system. Moreover, the fuse 20 can be used as a discriminator in a larger system since the fuse 20 allows a more sensitive load to be employed, which reduces possibility of a dormant failure occurring.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various non-limiting embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
