Segmented rotary transformer having a large diameter

Abstract

The invention relates to a rotary transformer that is intended to be installed around a rotating shaft, the rotary transformer being made up of a plurality of stator annular sectors (22a, 22b) and a plurality of rotor annular sectors (24a, 24b), the juxtaposition of these annular sectors (20) forming a stator ring and a rotor ring formed of elementary stator and rotor magnetic circuits having external (30) and internal (34) magnetic cores and first (32) and second (36) electrical windings to allow power to be transferred by electromagnetic induction between the stator rings and the rotor rings, the internal and external magnetic cores being separated by one and the same air gap present on either side of the internal magnetic core and at least the external magnetic cores have shoes at the air gap to prevent any discontinuity in the magnetic field lines as the movable shaft rotates.

Description

[0001] Description

[0002] Title of the invention: Large diameter segmented rotating transformer

[0003] Technical Field

[0004] The present invention relates to the field of power transfer between a fixed reference point and a rotating reference point for the electrical de-icing of the propeller blades of an aircraft turbomachine and relates to a single-phase rotating transformer used for the transmission of electrical energy by electromagnetic induction between first and second electrical windings of this transformer.

[0005] Prior art

[0006] On electric or hybrid aircraft, as on conventional aircraft, there are several surfaces to protect against frost on the fixed and rotating parts of the turbomachine. The protection envisaged for the rotating parts is generally exclusively electrothermal based on electric heating mats formed of layers of resistance covering the surfaces to be protected.

[0007] To ensure the transfer of power and therefore convey the electrical energy from the fixed part to the rotating part where the electric heating mats are installed, it is known to use a device called a "slip ring", the principle of which consists of rubbing several fixed conductive rings secured to the fixed part on circular conductive tracks secured to the rotating part, in order to create an electrical connection between the fixed part and the rotating part of the turbomachine.

[0008] Furthermore, it is known that due to the harsh environment (thermal, electromagnetic and vibration) existing in hybrid aircraft with numerous electrified engine loads, the integration of electrical equipment is a major challenge and must meet multiple constraints linked both to accessibility for assembly / disassembly and to the routing of power cables with large bending radii and services such as cooling.

[0009] There is therefore a current need for a reliable and long-life solution for transferring power from a fixed reference to a rotating reference applicable to large diameter rotating shafts and respecting the constraints of under-wing line replaceable equipment (LRU: Line Replaceable Unit).

[0010] Statement of the invention

[0011] The main aim of the present invention is therefore a large diameter rotating transformer, segmented into quarters, whose maintenance is facilitated and does not interfere with the other systems and modules of the aircraft turbomachine, despite its installation in a confined, constrained and difficult-to-access area. Another aim is to allow industrialization of this rotating transformer at a lower cost and by limiting material waste during manufacturing.

[0012] These aims are achieved by a rotating transformer intended to be installed around a rotating movable shaft, the rotating transformer being made up of a plurality of external annular stator sectors and a plurality of internal annular rotor sectors, the juxtaposition over 360° of these external annular stator and internal rotor sectors forming an external stator ring and an internal rotor ring made up of a set of elementary stator and rotor magnetic circuits, each of the elementary stator magnetic circuits comprising an external magnetic core and a first electrical winding and each of the elementary rotor magnetic circuits comprising an internal magnetic core and a second electrical winding to allow a transfer of electrical energy by electromagnetic induction between the external stator and internal rotor rings,the internal and external magnetic cores being separated by two air gaps present on either side of the internal magnetic core, characterized in that at least the external magnetic cores have expansions at the level of each of the two air gaps to avoid a discontinuity of the magnetic field lines during the rotation of the mobile shaft and in that the internal annular rotor sectors are identical and interchangeable with each other.,

[0013] Thus, with this contactless power transfer, an improvement in the reliability, lifespan and operating cost of the transformer is obtained. In addition, better accessibility to the transformer is possible, facilitating its integration into the systems and modules of the aircraft turbomachine. Such a rotating transformer is advantageously used for the electrical de-icing of the propeller blades of an aircraft turbomachine.

[0014] Preferably, the external annular stator sectors are identical and interchangeable with each other and the number of elementary stator and rotor magnetic circuits per annular sector is not identical to the stator and the rotor.

[0015] Advantageously, the external annular stator sectors are electrically interconnected with each other by interconnection parts accessible for assembly / disassembly through circumferential access hatches and the internal annular rotor sectors are electrically interconnected with each other and accessible for assembly / disassembly through the circumferential access hatches.

[0016] Preferably, the inner and outer magnetic cores are formed from a stack of laminations, wound laminations or a block of magnetic powder.

[0017] Advantageously, the stack of sheets is in the form of packets of sheets of a magnetic material such as FeSi, FeNi or FeCo, the wound sheets in the form of an amorphous or nanocrystalline magnetic material, and the block of magnetic powder in the form of amorphous powder.

[0018] Preferably, the outer magnetic core has a C or U shape terminated by the expansions at the air gap and the inner magnetic core has an H shape defining the expansions at the air gap.

[0019] Advantageously, the expansions are formed by bars having a notch allowing the branches of the C or U to be inserted therein and thus offer a larger contact surface between the branches and the bars. According to an exemplary embodiment, the external U-shaped magnetic core is produced by cutting into two parts a magnetic torus formed from a wound sheet metal and the expansions are produced by cutting into four quarter rounds a cylindrical magnetic torus of wound sheets.

[0020] According to another embodiment, the external magnetic core is made from a nesting of three U-shaped sheets of metal.

[0021] According to yet another embodiment, the external magnetic core is made from a C-shaped part, parts of which on either side of a central part have been machined to obtain the expansions at the air gap.

[0022] Brief description of the drawings

[0023] Other characteristics and advantages of the present invention will emerge more clearly from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not in any limiting nature and in which:

[0024] [Fig. 1] Figure 1 illustrates a part of an aircraft turbomachine incorporating a rotating transformer according to the invention,

[0025] [Fig. 2] Figure 2 shows a section of the rotating transformer of Figure 1,

[0026] [Fig. 3] Figure 3 shows a first example of stator and rotor magnetic circuits making up the rotating transformer district of Figure 2,

[0027] [Fig. 4] Figure 4 shows a second example of stator and rotor magnetic cores making up the rotating transformer district of Figure 2,

[0028] [Fig. 5] Figure 5 shows a third example of stator and rotor magnetic cores making up the rotating transformer district of Figure 2,

[0029] [Fig. 6] Figure 6 illustrates a stator variant for the third example of stator and rotor magnetic cores comprising the rotating transformer district of Figure 2, [Fig. 7] Figure 7 shows a fourth example of stator and rotor magnetic cores comprising the rotating transformer district of Figure 2, and

[0030] [Fig. 8] Figure 8 shows a fifth example of stator and rotor magnetic cores making up the rotating transformer district of Figure 2.

[0031] Description of the embodiments

[0032] The principle of the invention implemented is based on a segmentation of the rotating transformer into several annular sectors or quarters each having a mass and a replacement time compatible with a ground maintenance operation limiting the downtime of the aircraft, so that the replacement interventions (assembly / disassembly) are facilitated and can be carried out by conventional tools through dedicated access hatches, without having to disassemble or interfere with the other parts of the aircraft turbomachine.

[0033] As shown in Figure 1 which is a part of an aircraft turbomachine, the rotating transformer 10 according to the invention is mounted between a rotating transmission shaft 12 forming a rotating part of the turbomachine and a casing 14 forming a fixed part of the turbomachine, provided with circumferential access hatches 14a through which each of the annular quarters or sectors of the rotating transformer can be installed or easily removed for repair or maintenance and then reinstalled once these replacement operations have been carried out.

[0034] Figure 2 illustrates more precisely an annular sector or quarter 20 of the rotating transformer 10 which in the example illustrated comprises two redundant paths (bearing the references a and b) axially offset, each consisting of a fixed stator quarter 22a, 22b secured to the casing and a rotating rotor quarter 24a, 24b secured to the transmission shaft, the rotor and stator quarters of each path, mounted concentrically, being separated by an air gap (visible in the following figures). The rotating transformer formed by the juxtaposition over 360° of several quarters 20 has a large diameter, of the order of a meter or more, which allows the rotor to receive a transmission shaft also of large diameter, such as a propeller shaft.

[0035] According to the invention, the juxtaposition over 360° of these different annular sectors to the stator and to the rotor form an external stator ring and an internal rotor ring consisting of a plurality of single-phase elementary stator and rotor magnetic circuits respectively comprising a stator magnetic core 30 and a first electrical winding (primary 32) and a rotor magnetic core 34 and a second electrical winding (secondary 36), the stator and rotor magnetic cores being separated by the same air gap present on either side of the rotor magnetic core and the sectors being able to be electrically interconnected in series or in parallel for the transmission of electrical energy by electromagnetic induction between the first and second electrical windings of these elementary stator and rotor magnetic circuits. Both to the stator and to the rotor, the annular sectors are identical and interchangeable with each other.On the other hand, the number of these elementary magnetic circuits per annular sector is not necessarily identical to the stator and the rotor, the choice of the number of magnetic circuits in the stator and the rotor being guided by design considerations and optimization of transfer performance.

[0036] An annular sector on the stator or rotor is designed as an LRU (Line Replaceable Unit) which can be dismantled and replaced under the wing through the circumferential access hatches 14a. They are electrically interconnected by interconnecting parts (not referenced) which are also accessible for assembly / disassembly through the circumferential access hatches 14a.

[0037] It should be noted that in the illustrated case where the power transfer solution is redundant, an annular sector at the stator or rotor is made up of all the elements of two identical paths placed side by side in the axial plane.

[0038] Depending on the intended frequency of use, the type of material used for the magnetic core may be different. Thus, for low-frequency use, a stack in the form of packets of sheets of a magnetic material such as FeSi, FeNi or FeCo is considered for both the stator and the rotor. For medium or high-frequency use, a magnetic core made of wound sheet of amorphous or nanocrystalline type or in the form of a powder block of any other suitable magnetic material (for example, amorphous powder) is considered for the stator and the rotor. A mixture of materials is however possible with a stator made of medium- or high-frequency material and a rotor made of low-frequency material or vice versa.

[0039] Figures 3 to 8 show different possible topologies for each elementary magnetic circuit at the stator and at the rotor allowing the realization of the rotating transformer according to the invention. It will be noted that such a magnetic circuit can be installed horizontally (axial air gap as illustrated) or vertically (radial air gap). These topologies all have in common the fact that the stator magnetic cores (or external stator 30) have expansions 30a, 30b at each of the two air gaps 38a, 38b which correspond to the stator and which, by avoiding a discontinuity of the magnetic field lines during the rotation of the mobile shaft, improve the efficiency of the power transfer. The rotor magnetic cores (or internal rotor 34) can also have expansions 34a, 34b or not (see for example figures 5 and 6).It will be noted that, for reasons of simplification, the electrical windings 32, 36 which are not shown in figures 4 to 8 showing only the stator and rotor magnetic cores, can be wire or ribbon depending on the different integration and performance constraints to be respected, and the series of three lines appearing on the magnetic cores tend to show the arrangement of the sheets constituting them.

[0040] In Figure 3, corresponding to low-frequency use, the external or stator magnetic core 30 has a U-shape ending in expansions 30a, 30b at the two axial air gaps 38a, 38b. The internal or rotor magnetic core 34 has an H-shape defining expansions 34a, 34b at these two axial air gaps present on either side of the internal magnetic core 34.

[0041] In Figure 4 is shown an economical embodiment without wastage of materials corresponding to a medium or high frequency use and in which the internal magnetic core 40 has an H shape obtained by a stack of sheets in the vertical plane and the external magnetic core 42 is made up of an assembly of three parts, namely a U-shaped part 44 resulting from a cut into two parts of a magnetic torus formed from a wound sheet and two expansions 46, 48 resulting from a cut into four quarters of a round of a cylindrical magnetic torus of wound sheets. The shape of the expansions can of course be adapted for reasons of mass saving by modifying the width at the level of the junction surface between the expansion and the U-shaped part 44.

[0042] In Figure 5, the C-shaped external magnetic core 50 is cut out at the air gap to leave room for the addition of a bar 52, 54 on each side of the cutout to form the expansions between which the I-shaped internal magnetic core 56, therefore without expansions, is placed. As illustrated in Figure 6, these bars 52, 54 may advantageously each have a notch 58 allowing the branches 50a, 50b of the C-shaped part to be inserted therein and thus offer a larger contact surface between the two parts (C / bar).

[0043] In the embodiment of Figure 7, more specifically adapted to low frequency use and also without wasting materials when cutting, the internal magnetic core 60 also has an H shape by a stack of sheets in the vertical plane and the external magnetic core 62 is composed of a nesting of three packets of sheets 64, 66, 68 in a U shape.

[0044] Finally, Figure 8 shows another example of a particularly robust embodiment with an external magnetic core obtained by simply machining a C-shaped part 70 having an initial width equal to that of the expansions at the air gap as illustrated. The material corresponding to the parts 72, 74 and without touching the parts 76, 78 forming the expansions, is removed along the cutting lines illustrated in dotted lines in the figure to leave only the central part 80.

[0045] This produces a final magnetic core with a width less than the spread at the level of the passage of the electric winding. The internal magnetic core (not shown) can be H-shaped or I-shaped.

[0046] While reference has been made to the de-icing of propeller blades of an aircraft turbomachine as an application, other possible applications, particularly in the aeronautical industry, which can benefit from the use of rotating transformers include the feedback of information from torque sensors for variable blade setting in aircraft and propeller pitch setting in helicopters, for example. For such applications, the elimination of the conventional brush collector and its replacement with a rotating transformer is advantageous because it makes the equipment more reliable by eliminating the risk of breakdown created by brush wear.

Claims

Demands

1. Rotating transformer (10) intended to be installed around a rotating shaft (12), the rotating transformer being made up of a plurality of external annular stator sectors (22a, 22b) and a plurality of internal annular rotor sectors (24a, 24b), the 360° juxtaposition of these external annular stator and internal rotor sectors forming an external stator ring and an internal rotor ring made up of elementary stator and rotor magnetic circuits, each of the elementary stator magnetic circuits comprising an external magnetic core (30, 42, 52, 62, 70) and a first electrical winding (32) and each of the elementary rotor magnetic circuits comprising an internal magnetic core (34, 40, 56, 60, 76) and a second electrical winding (36) to allow a transfer of electrical energy by electromagnetic induction between the external stator and internal rotor rings,the internal and external magnetic cores being mounted concentrically and separated by two air gaps (38a, 38b) present on either side of the internal magnetic core, characterized in that at least the external magnetic cores (30) have flares (30a, 30b) at each of the two air gaps (38a, 38b) to avoid a discontinuity of the magnetic field lines during the rotation of the moving shaft (12) and in that the internal annular sectors of the rotor are identical and interchangeable with each other.

2. Rotating transformer according to claim 1, wherein the external annular sectors of the stator are identical and interchangeable with each other.

3. Rotating transformer according to claim 1, wherein the number of elementary stator and rotor magnetic circuits per annular sector is not identical to the stator and rotor.

4. Rotating transformer according to claim 1 or claim 2, wherein the external annular sectors of the stator are electrically interconnected with each other by interconnecting parts accessible for assembly / disassembly through circumferential access hatches (14a).

5. Rotating transformer according to claim 4, wherein the internal annular rotor sectors are electrically interconnected and accessible for assembly / disassembly through circumferential access hatches (14a).

6. Rotating transformer according to any one of claims 1 to 5, wherein the internal and external magnetic cores (30, 42, 52, 62, 70; 34, 40, 56, 60, 76) are formed from a stack of laminations, wound laminations or a block of magnetic powder.

7. Rotating transformer according to claim 6, wherein the lamination stack is in the form of lamination packs of a magnetic material such as FeSi, FeNi or FeCo, the wound laminations in the form of an amorphous or nanocrystalline magnetic material, and the magnetic powder block in the form of amorphous powder.

8. Rotating transformer according to any one of claims 1 to 7, wherein the outer magnetic core (30, 42, 52, 62, 70) has a C or U shape terminated by the flares (30a, 30b; 46, 48; 52, 54; 66, 68) at the air gap and the inner magnetic core (34, 40, 56, 60, 76) has an H shape defining the flares (34a, 34b) at the air gap or an I shape without flares.

9. Rotating transformer according to claim 8, wherein the flares (52, 54; 66, 68) are formed by bars having a notch (58) allowing the branches of the C or U to fit into it and thus provide a larger contact surface between the branches and the bars.

10. Rotating transformer according to claim 8, in which the external magnetic core (42) is formed by cutting into two parts of a magnetic torus formed of a wound sheet (44) and the flares are formed by cutting into four quarter-rounds of a cylindrical magnetic torus of wound sheets (46, 48).

11. Rotating transformer according to claim 8, in which the external magnetic core (62) is formed from an interlocking of three U-shaped laminations (64, 66, 68).

12. Rotating transformer according to claim 8, in which the external magnetic core is derived from a C-shaped part (70) of which parts (72, 74) on either side of a central part (80) have been machined to obtain the flares (76, 78) at the air gap.

13. Use of a rotating transformer according to any one of claims 1 to 12 for the electrical de-icing of propeller blades of an aircraft turbomachine.

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