FR2865187A1 - Jack screw`s load transfer detecting device for aircraft, has temperature sensor measuring temperature of left and right half-ball joints, and processor to trigger detection of load transfer, in response to overheating of joints - Google Patents

Abstract

The device has a temperature sensor (9) measuring temperature of left and right half-ball joints (7, 8) integrated with a secondary nut. The nut withdraws the load of a screw in case of failure of a primary nut, by allowing a sphere (6) and the joints to contact. The contact generates friction dissipated in the form of heat. A processor triggers detection of load transfer of a jack screw, in response to overheating of the joints. An independent claim is also included for a jack for activating a mobile unit of an aircraft, comprising a jack screw`s load transfer detecting device.

Description

The invention relates to so-called "fail-safe" screw jacks, that is to say the

  screw jacks whose aircraft and structure fasteners are doubled to increase the level of safety.

  Screw jack systems for actuating an aircraft movable member generally have two fasteners: a so-called aircraft clip fastener, through which the screw is connected to the aircraft structure and a fastener called a fastening structure, whereby the screw is connected via a nut to the movable member to be actuated.

  In normal operating mode, the screw-aircraft links (aircraft attachment) and screw-movable member (attachment structure) are provided respectively by so-called primary channels. In case of failure of the primary channel of a fastener, the connection is then taken by an emergency route, called secondary track.

  Thus known jack systems having at the structural fastener, an additional level of security in the presence of a second nut (secondary nut) which, separated from the screw by a slight clearance during normal operation, takes over the charging the primary nut in case of failure of the latter.

  The invention more particularly relates to systems for detecting the failure of a fastener, during a charge transfer from the primary to the secondary path.

  In the case of the structural fastener, the invention thus relates to the detection of the transfer of load from the primary nut to the secondary nut.

  The invention is applicable to screw jacks, for example when these jacks are used for the orientation of an aircraft adjustable horizontal plane (PHR).

  A fail-safe device, certainly safe, presents the danger that a functioning resting only on the secondary way (for example the secondary nut in the case of the fastener structure), after failure of the primary way (the primary nut ), is not detected. The device then no longer has its extra level of security, and thereby loses its initial interest.

  We seek here to indicate this mode of operation to avoid a dormant failure mode.

  Typically, in this type of device, we have adopted, for the fastener structure, secondary nuts that can seize when operating with the screw, so that they can continue to perform the function of transmitting the movement.

  However, seizure can often not appear. The forces during the flight may for example not be so important that the secondary nut is caught in contact with the screw.

  The object of the invention is to provide a movable member actuating cylinder comprising, both at the level of the aircraft fastener and the structure fastener, a device for detecting the transfer of charge on the secondary pathway making it possible to remedy at the onset of a dormant failure.

  For this purpose, the invention proposes, according to a first aspect, a device for detecting the transfer of the load of a mobile actuator actuator screw from a primary track to a secondary track, said secondary track being arranged to take up the load of the screw in the event of failure of the primary track, in particular by bringing into contact a workpiece connected to the screw and a part secured to the secondary track, said contact generating friction dissipating in the form of of heat, characterized in that it comprises: E means for measuring the temperature of said integral part of the secondary channel, and É means for triggering said detection in response to the heating of said piece related to the secondary track.

  According to another aspect, the invention provides a movable member actuating cylinder comprising such a detection device at its plane attachment.

  According to yet another aspect, the invention proposes a movable member actuating cylinder 30 comprising such a detection device at its structure attachment.

  Other objects, features and advantages of the invention will appear on reading the detailed description which follows, with reference to the appended figures in which: FIG. 1 is a simplified sectional view of a device according to FIG. invention for detecting the failure of the primary track of the fastener structure of a screw jack system; FIG. 2 is a simplified sectional view of a device according to the invention for detecting the failure of the primary path of the aircraft fastener of a screw jack system.

  As seen previously, a screw jack system for actuating an aircraft moving member comprises two fasteners: an aircraft fastener through which the screw is linked to the structure of the aircraft (fuselage) and a fastener structure by which the screw is connected via a nut to the movable member to be actuated.

  Each of these fasteners has a secondary backup channel, able to resume the load of the screw in case of failure of the primary path.

  The detection device according to the invention can be used to detect the failure of the primary track of one or other of the aircraft and structure fasteners.

  With reference to FIG. 1, the following description of the device according to the invention relates more particularly to the fastening structure.

  In normal operation, the primary nut, here ball, is loaded and ensures the transmission of the load. The primary nut for example transmits its movement to an adjustable horizontal plane (PHR) of an aircraft.

  The secondary nut has, next to the pitch of the screw, a clearance sufficient to not be loaded in the case of normal operation where the primary nut takes charge.

  Typically, it is expected that each of the primary and secondary nuts has a connection of its own with the actuated member. Following a failure of the primary track, the secondary track resumes the load via the secondary nut.

  The transfer of load on the secondary nut is then done by loading the own connection of the secondary nut and unloading the own connection of the primary nut.

  The secondary nut is thus mechanically placed on the path of the charges between the structure of the aircraft and the movable member, and comes into contact with the screw.

  More specifically, the threads of the secondary nut come into contact with the threads of the screw, the clearance between the secondary nut and the screw disappearing.

  Due to the load of traction or compression of the secondary nut on the screw and the rotation of the screw which inclines the movable member, this contact generates friction (friction).

  This friction dissipates energy in the form of heat in the screw and in the secondary nut.

  As a purely illustrative example, it is noted here that a heating of the order of 60 C can be observed over the duration of a flight. The invention proposes to measure the temperature on the secondary nut and to detect the rise of this temperature following a failure of the primary channel.

  The failure of the primary route is preferably noted over a period less than that of a flight. FIG. 1 represents a sectional view of a secondary nut 1 mounted on a screw jack system 2.

  At least one temperature probe 3 is mounted on the secondary nut 1 so as to provide a measurement of the temperature of said secondary nut 1.

  Said probe 1 is connected to a processing unit (not shown) adapted to trigger the detection of the failure of the primary path as soon as sufficient heating of the secondary nut is observed.

  Preferably, the device according to the invention compares said temperature measurement on the secondary nut with a reference temperature.

  Said reference temperature makes it possible to reflect the temperature of the screw jack system apart from the case of transferring the charges onto the secondary channel.

  Said reference temperature is, for example, that recorded on a reference part 4 by a reference probe.

  Said reference piece 4 has thermal characteristics identical to those of the secondary nut.

  Said reference piece 4 is advantageously arranged close to the secondary nut 1. It can be mounted on the same attachment piece as said secondary nut so as to be secured thereto.

  In this way, it is ensured that the temperature fluctuations which take place outside the case of transfer of forces on the secondary path do not cause the triggering of the detection.

  Said processing unit is here adapted to measure the temperature difference between the friction piece (loaded secondary nut) and the environment (reference part) and to trigger the detection as soon as this difference is greater than a given value.

  Preferably, the device according to the invention may comprise several temperature probes (both at the secondary nut and at the reference part) so as to be redundant.

  Referring to Figure 2, there is provided a device according to the invention for the detection of a load transfer at the aircraft attachment of a cylinder system.

  Such an aircraft fastener is generally provided by means of an anchor bar with the structure of the aircraft.

  At this aircraft attachment, the screw (not shown) of the cylinder system is thus rotatably connected with a sphere 6 of a primary attachment bar to the structure of the aircraft.

  During normal operation, when the primary path is loaded, the sphere 6 rotates freely in a ball joint constituted by two half-rings (respectively a half-left knee 7 and a half-right knee 8) integral with the secondary path.

  The appearance of charges on the secondary track, following the failure of the primary track, causes the contact 6 of the sphere 6 on one of the half-ball joints 7, 8 (loading tension or compression) of the secondary fastener.

  The applied charges and the movement of the movable member will dissipate energy in the form of heat, in particular because of friction with the ball-and-socket contact.

  At least one temperature probe 9 is disposed on one of the half-pipes (here the right half-ball joint 8) in order to provide a measurement of the temperature and an indication as to the heating of the friction parts.

  A reference piece 10 on which is disposed at least one reference probe 11 may also be used for a relative temperature difference to be detected.

  Of course, such a reference piece has characteristics identical to those previously mentioned for the fastening structure.

  Said reference piece may thus be integral with the secondary fastener, and more specifically, as is the case in FIG. 2, secured to the right half-ball joint 8.

  Finally, to ensure the redundancy of the device according to the invention, a plurality of probes can be used, both at the reference part and the friction parts.

  It will be recalled here that the invention also relates to actuating cylinders for a movable member comprising a detection device such as that described in the previous description, at its structural attachment and / or at its plane attachment. .

Claims (15)

  1. Device for detecting the transfer of the load of a movable actuator actuator screw from a primary track to a secondary track, said secondary track being arranged to take up the load of the screw in case of failure of the primary track, in particular by contacting a workpiece (6) connected to the screw and a part (7, 8) integral with the secondary track, said contact generating friction dissipating in the form of heat, characterized in what it comprises: É means (9) for measuring the temperature of said part (7, 8) integral with the secondary channel, and É means for triggering said detection in response to the heating of said part ( 7, 8) related to the secondary path.   2. Device according to the preceding claim, characterized in that it further comprises a part (10) of reference and measuring means (11) of the temperature of said reference part, said detection being triggered when the temperature difference between said part (7, 8) related to the secondary path and said reference part (10) is greater than a given threshold.   3. Device according to the preceding claim, characterized in that said reference part (10) has identical thermal characteristics to that of said part (7, 8) connected to the secondary path and is positioned near the latter so as to the fluctuations in the temperature of the external environment have the same effect on said part connected to the secondary track and on said reference piece.   4. Device according to the preceding claim, characterized in that said reference piece (10) is integral with said part (7, 8) connected to the secondary path.   5. Device according to one of claims 2 to 4, characterized in that said means for measuring the temperature of said integral part of the secondary path comprise at least one temperature sensor disposed on said integral part of the secondary path and in said means for measuring the temperature of said reference piece comprise at least one temperature probe (11) disposed on said reference piece.   6. Device according to claim 5, characterized in that said means for measuring the temperature of said integral part of the secondary channel comprise at least two probes (9) and in that said means for measuring the temperature of said piece of reference comprise at least two probes (11) so as to ensure the redundancy of said device.   7. movable member actuating cylinder comprising a screw and a fastener structure by which the screw is connected to the movable member, said structure fastener being doubled in that it comprises a primary track and a secondary actuation channel; of said member, said secondary channel being intended to provide for a failure of the primary channel, two nuts, one primary and one secondary (1) being for this purpose engaged around the screw (2) and each connected to the movable member via a clean connection, a relative movement between the screw and the nuts producing said actuation, the secondary nut (1) being arranged to resume the load of the screw in the event of failure of the primary nut, said secondary nut then coming into contact with the screw, said contact generating friction dissipating in the form of heat, said jack being characterized in that it comprises: means (3) for measuring the temperature of the secondary nut (1), and E means for detecting the transfer of the load of the screw from the primary track to the secondary track in response to the heating of said secondary nut (1).   8. Cylinder according to the preceding claim, characterized in that it further comprises a part (4) of reference and measuring means (5) of the temperature of said reference part, said detection being triggered as soon as the The temperature difference between the secondary nut (1) and said reference piece (4) is greater than a given threshold.   9. Cylinder according to the preceding claim, characterized in that said reference part (4) has thermal characteristics similar to that of said secondary nut (1) and is positioned near the latter so that the temperature fluctuations of the external environment influences in the same way on said secondary nut and on said reference piece.   10. Cylinder according to the preceding claim, characterized in that said reference piece (4) is integral with said secondary nut (1).   11. Aircraft moving member actuating cylinder comprising a screw and an aircraft fastener through which the screw is connected to the aircraft, said aircraft fastener being doubled in that it comprises a primary track and a secondary track. attached to the structure of the aircraft, said secondary path being provided to compensate for a failure of the primary track, the screw being for this reason connected in rotation with a sphere (6) of a primary fastening bar to the aircraft, said sphere (6) freely rotating in a ball joint (7, 8) integral with a secondary attachment (12) to the aircraft, said ball being arranged to take up the load of the screw in the event of failure of the primary track said sphere then coming into contact with said ball joint and said contact generating i0 friction dissipating in the form of heat, said cylinder being characterized in that comprises: E means (9) for measuring the temperature of the ball joint (7, 8 ) secured to the secondary fastener, and E means for detecting the transfer of the load of the screw from the primary channel to the secondary channel in response to the heating of said ball joint.   12. A cylinder according to the preceding claim, characterized in that it further comprises a reference piece (10) and measuring means (11) for the temperature of said reference piece, said detection being triggered as soon as the The temperature difference between the ball (7, 8) and said reference piece (10) is greater than a given threshold.   13. Cylinder according to the preceding claim, characterized in that said reference part (10) has thermal characteristics similar to that of said ball (7, 8) and is positioned near the latter so that the fluctuations of temperature of the external environment influences in the same way on said ball and on said reference piece.   14. Cylinder according to the preceding claim, characterized in that said reference piece (10) is integral with said ball (8).   15. Aircraft movable member actuating cylinder comprising a screw, a structure fastener by which the screw is connected to the movable member, an aircraft fastener through which the screw is connected to the aircraft, said aircraft fasteners and structure being doubled in that they each comprise a primary track and a secondary track, each of the secondary tracks being intended to provide for a failure of the corresponding primary track, in particular by bringing into contact a workpiece connected to the screw and of an integral part of the secondary track, said contact generating friction dissipates in the form of heat, said jack being characterized in that, for each of said aircraft and structure fasteners, it comprises: E measuring means of the temperature of said integral part of the secondary path, and É means for detecting the transfer of the load of the screw from the primary path to the secondary path for the link concerned, in response to heating of said part connected to the secondary path.