EP2348571B1 - Compact waveguide actuator, phase stable waveguide and multiplexer using this actuator. - Google Patents

Description

The present invention relates to a compact thermoelastic actuator for a waveguide, a phase stability waveguide and a multiplexing device comprising such an actuator. It applies in particular to the compensation of the volume changes of a waveguide subjected to temperature variations and more particularly to the waveguides of the multiplexers integrated into satellite space equipment.

Multiplexers or demultiplexers also called OMUX (in English: Output Multiplexer) integrated in particular in space equipment are subject to significant temperature variations. These OMUX generally comprise several channels interconnected by at least one waveguide, also called manifold, whose dimensional variations due to temperature variations induce an offset of the geometric distance between the channel connection ports of OMUX and phase shifts in the guided waves. These phase shifts cause a malfunction of the equipment and can for example cause mismatches of the OMUX channels.

To solve this problem, it is known to produce the waveguide in a material with a low thermal expansion rate CTE (in English: Coefficient of Thermal Expansion) such as titanium or an alloy of iron and nickel, for example the invar (registered trademark). However, space equipment is generally made of low density materials such as aluminum which has a high coefficient of thermal expansion, assemblies with low CTE waveguides cause mechanical stress during temperature variations. between structures that can cause malfunctions.

The document US 5,428,323 discloses a method of compensating the thermal expansion of a rectangular section waveguide by applying a deformation on its two side walls of smaller width so as to provide phase stability. The deformation is applied by small-side orthogonal spacers fixed between the short sides of the waveguide and a low CTE holding structure disposed around the waveguide. During a temperature variation, the spacer pieces lengthen or shrink and pull or support orthogonally on the short sides, which forces the short sides of the waveguide to deform along an axis orthogonal to these small sides. However, this technology requires the use of a holding structure arranged around the waveguide.

The document EP 1,909,355 discloses another phase stability waveguide assembly in which lever mechanisms are rotated about pivots under the action of temperature variations and compensate for larger variations in waveguide size by temperature function by pulling or pressing orthogonally on the short sides of the waveguide. However, this assembly is complex, cumbersome and can hinder the positioning of the adjacent channels and the mechanical interfaces of the OMUX near the waveguide, particularly in the context of a compact configuration in which the channels are arranged in staggered rows. on both sides of the waveguide.

The document CA 2,432,876 discloses another phase stability waveguide assembly in which the short sides of the waveguide have a curved initial length and are constrained in a lateral direction of the waveguide by a plurality of low CTE plates placed sideways side by side along the waveguide laterally on either side of each small curved side. The expansion or contraction of the short sides is restricted by the side plates while the long sides are free to expand or contract. This assembly has the disadvantage of requiring pre-bending the short side of the waveguide while laterally and symmetrically ribbing the upper and lower portions of the waveguide, thus reducing the positioning latitude of the channels relative to the guide of the waveguide. Waveform as well as the mechanical interfaces of the OMUX near the waveguide.

The document EP 2006951 discloses another phase stability waveguide assembly with actuators consisting of a pair of shoulder straps connected to longitudinal ribs secured to the guide. The straps induce, by thermal expansion, a rotation of the ribs deforming the short sides of the waveguide to compensate for variations in size.

The object of the invention is to provide a thermoelastic waveguide actuator for ensuring the phase stability of the waveguide and not having the disadvantages of existing devices. In particular, the invention relates to a thermoelastic actuator for simple waveguide to be implemented, of small size, optimized to minimize the volume occupied near the waveguide and the channels, and particularly adapted to a technology of 'OMUX with vertical structure.

For this, the invention relates to a compact thermoelastic waveguide actuator comprising at least two identical stress parts made of a first material having a first coefficient of thermal expansion and a holding part made of a second different material. of the first material and having a second coefficient of thermal expansion less than the first coefficient of thermal expansion, characterized in that the force pieces have a length which extends in a longitudinal direction Y between two outer and inner ends, are mounted head -beach one beside the other parallel to the Y direction and are linearly offset relative to each other, along the longitudinal axis Y, and in that the holding piece has two ends upper and lower and a middle zone located in a central region of the holding part between the two upper ends the lower and upper ends, the upper and lower ends of the holding part being respectively connected to the outer ends of each piece of force and the inner ends of each piece of force being positioned under the median zone of the holding piece.

Advantageously, the linear shift of the workpieces relative to each other, along the longitudinal axis Y, is equal to half their length.

Advantageously, the force parts are filiform and may be, for example, longitudinal bars.

Preferably, the force parts are axially symmetrical. They may for example have an inner fork-shaped end having at least two fingers.

In a particular embodiment, the actuator comprises at least four pieces of effort mounted head to tail two by two and the fingers of the forks consecutive pieces of effort mounted in the same direction are intersecting one above the other .

Advantageously, each finger has a point of attachment and the attachment points of two interlocking fingers belonging to two consecutive pieces of effort mounted in the same direction are connected together.

The invention also relates to a phase stability waveguide having a rectangular cross-section having two long sides and two small opposite sides and having at least two external longitudinal ribs, respectively upper and lower, located symmetrically in the extension of the long sides. respectively on the two small opposite sides of the waveguide, the two ribs being off-axis with respect to a median axis of the short sides, the waveguide comprising at least one compact thermoelastic actuator, the actuator having its axis longitudinally positioned parallel to a large side of the rectangular waveguide and the inner ends of the actuator force parts located below the median zone being respectively fixed to the outer longitudinal ribs of the waveguide.

The invention finally relates to a multiplexing device comprising at least one phase stability waveguide.

• figures 1 et 2: deux schémas, respectivement en perspective et en vue éclatée, d'un premier exemple d'actionneur thermo-élastique compact pour guide d'ondes, selon l'invention ;
• figures 3a et 3b : deux vues en perspective et de dessous d'un deuxième exemple d'actionneur thermo-élastique compact pour guide d'ondes, selon l'invention ;
• figure 4 : une vue en coupe transversale d'un guide d'ondes à section rectangulaire à température ambiante équipé de l'actionneur thermo-élastique compact de la figure 2, selon l'invention ;
• figures 5a et 5b : deux vues, respectivement en coupe et en perspective, du guide d'ondes de la figure 4 lorsque la température croît, selon l'invention ;
• figures 6a, 6b, 6c : des vues en perspective d'un guide d'ondes rectangulaire équipé de plusieurs actionneurs thermo-élastiques compacts, 6a, 6b : les actionneurs sont tous répartis contre un même côté du guide - 6c : le guide d'ondes comporte plusieurs nervures en quinconce et les actionneurs sont positionnés en quinconce contre deux côtés du guide d'ondes, selon l'invention ;
• figures 7 et 8 : deux vues, respectivement en perspective et en coupe transversale, de deux exemples de multiplexeurs avec des canaux de topologie verticale, selon l'invention.

Other features and advantages of the invention will become clear in the following description given by way of purely illustrative and non-limiting example, with reference to the attached schematic drawings which represent:

• Figures 1 and 2 two diagrams, respectively in perspective and in exploded view, of a first example of compact thermoelastic actuator for waveguide, according to the invention;
• Figures 3a and 3b : two views in perspective and from below of a second example of compact thermoelastic actuator for waveguide, according to the invention;
• figure 4 : a cross-sectional view of a rectangular waveguide at room temperature equipped with the compact thermoelastic actuator of the figure 2 according to the invention;
• Figures 5a and 5b : two views, respectively in section and in perspective, of the waveguide of the figure 4 when the temperature increases, according to the invention;
• Figures 6a , 6b , 6c : perspective views of a rectangular waveguide equipped with several compact thermoelastic actuators, 6a, 6b: the actuators are all distributed against the same side of the guide - 6c: the waveguide has several ribs staggered and the actuators are staggered against two sides of the waveguide according to the invention;
• Figures 7 and 8 : two views, respectively in perspective and in cross section, of two examples of multiplexers with vertical topology channels, according to the invention.

The first example of an actuator represented on the Figures 1 and 2 and the second example of actuator shown on the Figures 3a and 3b are of elongate shape along a longitudinal axis Y and comprise an even number of identical force pieces 10a, 10b, 10c, 10d, 30a, 30b made of a first material having a first coefficient of thermal expansion CTE1 and a holding piece 11 , 31 made in a second material different from the first material and having a second coefficient of thermal expansion CTE2 lower than the first coefficient of thermal expansion CTE1. For example, the first material is a thermal conductive material with a high coefficient of thermal expansion such as aluminum and the second material is a material with a low coefficient of thermal expansion. thermal expansion such as titanium or an alloy of iron and nickel such as Invar. The stresses 10a to 10d, 30a, 30b and the retaining piece 11, 31 are of elongated shape along a longitudinal axis Y and may have, as on the Figures 1 and 2 , Axial symmetry with respect to the longitudinal axis Y. The stresses are filamentary and may for example be substantially straight bars, of small width and thin as on the Figures 3a and 3b or have a forked end with two fingers as on the Figures 1 and 2 or have any other shape with axial symmetry with respect to the Y axis, elongate in the Y direction and preferably narrow in the X and Z directions orthogonal to the Y direction. The length and the thickness of the effort pieces may have values vary widely depending on the application. By way of non-limiting example, the workpieces may be a few millimeters thick and several centimeters in length, or different values of a factor of ten and even beyond.

The stresses 10a, 10b or 10c, 10d or 30a, 30b are mounted head to tail next to each other in the same plane XY and so that two pieces of force mounted vis-à-vis are linearly offset from one another along the longitudinal axis Y by a distance of approximately half their length. Each piece of force has an inner end 12, 13, 32 disposed in a central zone 14, 34 of the actuator 15, 35 and an outer end 16, 36, the inner ends 12, 13, 32 and outer 16, 36 being provided with fixing points. In the case of the example, represented on the Figures 1 and 2 , where the stresses have fork-shaped inner ends with two fingers 17, 18, the fingers 17, 18 of the forks belonging to different consecutive pieces of effort mounted in the same direction 10a, 10c or in the opposite direction 10b, 10d, intersect one above the other in the median zone 14 of the actuator 15. In this case, the two innermost interlocking fingers belonging to two pieces of force mounted in the same direction 10a, 10c are connected together at their point of attachment and it is the same for the two members of force mounted in opposite directions 10b, 10d. The holding piece 11, 31 has two opposite ends, respectively upper 20, 37 and lower 21, 38 and a median zone situated between the two upper and lower ends, the median zone of the holding piece 11, 31 corresponding to the central zone 14, 34 of the actuator 15, 35. The holding piece is mounted on an upper face of the force pieces so that the median zone 14, 34 of the retaining piece 11, 31 covers at least partially the inner ends 12, 13, 32 of the force parts and that its two opposite ends 20, 21, 37, 38 are fixed to the attachment points of the outer ends 16, 36 pieces of effort. The holding piece 11, 31 has a small thickness relative to its length, the length and the thickness of the holding piece being of the same order of magnitude as those of the force pieces, and may for example have an asymmetrical shape substantially planar which comprises a median zone 14, 34 of width equal to or greater than the width of the workpieces provided with lateral recesses 39, 40 arranged in the thickness of the holding piece, facing the attachment points of the ends 12, 13, 32 of the stresses, as shown on the Figures 3a and 3b . Alternatively and preferably, the retaining piece may have a symmetrical shape that includes a central zone comprising a central recess 22 so as to allow access to the fastening points of the actuator located at the ends of the fingers of the force parts as shown on the Figures 1 and 2 . The holding piece 11, 31 may have any other shape, elongate in the longitudinal direction Y, having a central zone at least partially covering the inner ends of the force parts and two opposite ends fixed to the attachment points of the outer ends of the parts. effort.

The figure 4 represents a cross-sectional view of an assembly of the compact thermoelastic actuator of the figure 2 on a waveguide 41 rectangular section at room temperature. The rectangular waveguide 41 has in cross section, two small sides 43a, 43b and two long sides 44 opposite two by two. The waveguide also comprises two external longitudinal ribs 42a, 42b arranged symmetrically respectively on each of the short sides 43a, 43b, in the extension of the long sides 44. The two external ribs 42a, 42b are parallel to each other, extend over approximately half the width of the short sides 43a, 43b and are off-axis with respect to the median axis of the short sides. The ribs 42a, 42b are preferably cut in the mass, and therefore integral with the waveguide 41. The sides 43a, 43b of the waveguide 41 have a wall finer than the long sides 44 so that it is more flexible and can be deformed under the action of tensile or compressive forces.

The median zone 14 of the actuator 15 is fixed on one of the long sides 44 of the rectangular waveguide 41 and simultaneously with the two longitudinal ribs 42a, 42b situated respectively on the two opposite small sides 43a, 43b of the guide of FIG. 41. The fixing can be achieved for example by means of fixing screws 45 mounted in threaded holes arranged, at the attachment points, in the inner ends 12, 13 of the effort pieces 10a to 10d and passing through one or the other longitudinal ribs 42a, 42b. The lower faces of the inner ends 12, 13 of the force parts 10a to 10d are in contact with the long side 44 and the ribs 42a, 42b of the waveguide 41, the upper faces of the inner ends 12, 13 of the parts of FIG. 10a to 10d are arranged under the median zone of the holding part 11. The geometry of the actuator 15 being axially symmetrical and the workpieces 10a to 10d being mounted head to tail, the fingers 17, 18 of the parts 10a and 10c effort oriented in the same direction are connected to the same rib 42b, the fingers 17, 18 of 10b and 10d force parts oriented in an opposite direction are symmetrically connected to the opposite rib 42a. In the example of the symmetrical actuator shown in Figures 1, 2 and 4 four workpieces 10a to 10d each having two fingers 17, 18 are mounted head to tail in pairs, two of the workpieces 10a, 10c being oriented in the same direction in which the fingers are fixed on the lower rib 42b of the waveguide 41, two other pieces of force being oriented in the same opposite direction in which the fingers are fixed on the upper rib 42a of the waveguide 41. The two interlocking fingers the innermost belonging to two pieces of force in the same direction are connected together, the two outermost fingers are not intersecting and are fixed only to a rib. The four fingers oriented in the same direction are respectively connected to the same rib at three different attachment points.

The Figures 5a and 5b represent two views, respectively in section and in perspective, of the assembly of the figure 4 when the temperature rises. When the temperature varies, the waveguide and the ribs made in The same high-CTE material, such as for example aluminum, expands or contracts which results in a phase shift of the electric waves propagating in the waveguide. The stress parts made of a material with a high CTE, preferably an electrical conductor, which may be identical to or different from the material used for the waveguide, are connected to the ribs of the waveguide by means of the connecting screws. and are therefore subject to the same temperature variations as the waveguide. These pieces of effort will therefore also expand or contract. However, the holding piece made of a low CTE material such as invar, for example, will expand much more weakly than the workpieces, keep a length very close to its initial length and maintain an almost constant distance between the parts. outer ends 16 of the stress pieces. The large difference between the coefficients of thermal expansion CTE1 and CTE2 thus makes it possible to generate a relative movement between the parts of force fixed on the upper rib and the parts of force fixed on the lower rib. The expansions or contractions of the effort pieces will thus result in cross-displacements of the fingers 17, 18 of the forks located at the inner ends of the workpieces 10a to 10b. The fingers will move symmetrically relative to each other, arching and apply compression or traction forces on the ribs of the waveguide through the connecting screws. The traction or compression forces on the ribs will result in a rotation of the ribs on themselves and cause deformation of the short sides of the waveguide. The geometry of the actuator 15 being axially symmetrical, the fingers 17, 18 being symmetrically intercrossed relative to each other and respectively connected in three different attachment points to the two opposite ribs 42a, 42b, the forces are applied simultaneously and symmetrically on the two ribs 42a, 42b. The displacement of the force parts is proportional to both the temperature, the length of the parts of effort between the two outer ends in the longitudinal direction, and the coefficient of expansion of the workpieces. The outer ends 16 of the force parts and the ends 20, 21 of the holding part are connected only to each other and to no other part. The use of four pieces of effort makes it possible to better distribute the efforts on the ribs and to improve the transmission of the compression or traction movement, but it is also possible to use only two more massive workpieces as shown in Figures 3a and 3b or an even number of pieces of effort greater than four. Alternatively, it is also possible to use an odd number of pieces of effort.

The Figures 6a , 6b and 6c represent perspective views of a rectangular waveguide equipped with several compact thermoelastic actuators according to the invention.

On the Figures 6a and 6b , the waveguide comprises two upper and lower outer longitudinal ribs 42a and 42b respectively fixed or cut in the mass, on its upper and lower walls corresponding, in cross section, to the two small opposite sides 43a, 43b of the rectangular section of the waveguide. The two upper and lower ribs are off-axis with respect to the median axis of the upper and lower walls and extend symmetrically in the extension of a sidewall of the corresponding waveguide, in cross section, to a long side 44 of the rectangular section. The actuators are distributed at regular intervals along the rectangular waveguide, against the same sidewall, and comprise parts of force 10a to 10d fixed, by their median zone, parallel to a sidewall of the waveguide on both upper and lower veins. On the Figure 6c , the waveguide comprises several upper and lower ribs arranged in staggered rows and inlet ports 60 on its two sides and the actuators 15 are arranged in staggered rows on both sides of the waveguide on either side of each of the input ports 60.

The Figures 7 and 8 represent respectively, in perspective and in cross section, two examples of multiplexers, also called OMUX, comprising microwave filters 62 each having an output connected to an access 60 of a common rectangular waveguide 41. The accesses 60 of the rectangular waveguide are arranged at regular intervals on its two sides of larger size corresponding to the long sides 44 of the rectangular section. The filters 62 are arranged parallel to each other and are fixed vertically on a common support 63. The waveguide is disposed horizontally between two rows of filters connected to the accesses on its two sides. The thermoelastic actuators 15 are visible on the cross section of the figure 8 . This figure shows that when the microwave filters 62 are arranged vertically, the space available between the filters for the thermoelastic actuators 15 is very limited. The actuator of the invention extends essentially in a longitudinal direction Y and is very compact in the other directions, which makes it possible to easily insert it between two consecutive filters, its longitudinal axis Y being placed parallel to the vertical axis filter channels.

Although the invention has been described in connection with particular embodiments, it is obvious that it is not limited thereto and that it includes all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims (13)

1. A compact thermo-elastic actuator for a waveguide comprising at least two identical stressing parts (10a, 10b, 10c, 10d, 30a, 30b) produced from a first material having a first thermal expansion coefficient CTE1 and a holding part (11, 31) produced from a second material different from the first material and having a second thermal expansion coefficient CTE2 below the first thermal expansion coefficient CTE1, characterised in that said stressing parts (10a, 10b, 10c, 10d, 30a, 30b) have a length that extends along a longitudinal axis Y between two external (16, 36) and internal (12, 13, 32) ends, are mounted head-to-tail one next to the other parallel to the axis Y and are linearly offset relative to one another along the longitudinal axis Y, and in that said holding part comprises two upper and lower ends and an intermediate zone located between said two upper and lower ends, said upper and lower ends of said holding part (11, 31) respectively being connected to said external ends (16, 36) of each stressing part (10a, 10b, 10c, 10d, 30a, 30b) and said internal ends (12, 13, 32) of each stressing part being positioned under the intermediate zone (14, 34) of said holding part (11, 31).
2. The actuator according to claim 1, characterised in that the linear offset of said stressing parts (10a, 10b, 10c, 10d, 30a, 30b) relative to one another along the longitudinal axis Y is equal to half of their length.
3. The actuator according to claim 1, characterised in that said stressing parts (10a, 10b, 10c, 10d, 30a, 30b) are filiform.
4. The actuator according to claim 1, characterised in that said stressing parts (30a, 30b) are longitudinal bars.
5. The actuator according to claim 1, characterised in that said stressing parts (10a, 10b, 10c, 10d) are axially symmetrical.
6. The actuator according to claim 5, characterised in that said stressing parts (10a, 10b, 10c, 10d) comprise an internal end (12, 13) in the shape of a fork comprising at least two prongs (17, 18).
7. The actuator according to claim 6, characterised in that it comprises at least four stressing parts (10a, 10b, 10c, 10d) mounted head-to-tail pairwise, and in that said prongs (17, 18) of the forks of the consecutive stressing parts mounted in the same direction (10a, 10c or 10b, 10d) are interleaved one above the other.
8. The actuator according to claim 7, characterised in that each finger (17, 18) comprises a fixation point, and in that the fixation points of two interleaved prongs belonging to two consecutive stressing parts (10a, 10c or 10b, 10d) mounted in the same direction are connected together.
9. A waveguide with phase stability comprising a rectangular transverse section with two large sides (44) and two small opposite sides (43a, 43b) and comprising at least two external longitudinal ribs, upper (42a) and lower (42b), respectively, symmetrically located in the extension of the large sides (44), respectively on the two opposite small sides (43a, 43b) of said waveguide (41), characterised in that it comprises at least one compact thermo-elastic actuator (15, 35) according to any one of the preceding claims, said actuator (15, 35) having its longitudinal axis Y positioned parallel to a large side (44) of said rectangular waveguide (41) and said internal ends (12, 13, 32) of said stressing parts of said actuator located under the intermediate zone (14, 34) being respectively fixed on said external longitudinal ribs (42a, 42b) of said waveguide (41).
10. The waveguide with phase stability according to claim 9, characterised in that it comprises a plurality of compact thermo-elastic actuators (15, 35) placed against the same large side (44) of said waveguide (41).
11. The waveguide with phase stability according to claim 9, characterised in that it comprises a plurality of upper and lower external longitudinal ribs disposed in a symmetrical and staggered manner on said two opposite small sides (43a, 43b) of said waveguide (41), and in that it comprises a plurality of compact thermo-elastic actuators (15, 35), with said thermo-elastic actuators being placed in a staggered manner against each of the large sides (44) of said waveguide (41).
12. The waveguide with phase stability according to claim 9, characterised in that said actuator (15, 35) comprises at least two stressing parts (10a, 10c) mounted head-to-tail, with each stressing part comprising an internal end (12, 13) in the shape of a fork comprising at least two prongs (17, 18), and in that said two prongs (17, 18) of the same fork are fixed to the same lower (42b) and upper (42a) rib, respectively.
13. A multiplexing device, characterised in that it comprises at least one waveguide (41) with phase stability according to any one of claims 9 to 12.

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