Device for measuring the rotational speed of an aircraft propeller

Abstract

Device (210) for measuring a rotational speed of an aircraft propeller (211), comprising: - an optical speed sensor (220); - an optical fiber (230) connected to the optical speed sensor and intended to be connected to a control unit of the aircraft; and - at least one target (251, 252) configured to follow the rotation of the propeller, the optical speed sensor being configured to detect the target.

Description

[0001] Description

[0002] Title of the invention: Device for measuring the rotation speed of an aircraft propeller

[0003] Technical Field

[0004] The present invention relates to the general field of phase synchronization between the propellers of an aircraft, and more particularly to the measurement of the rotational speed of these propellers to enable such synchronization.

[0005] Prior art

[0006] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various carbon emission restrictions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new aircraft types and to those currently in operation, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been mobilizing for several years now to contribute to the fight against climate change.

[0007] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of aircraft.

[0008] Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity. This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, in particular through the materials used and lighter onboard equipment, the development of the use of electric technologies to provide propulsion, and, as essential complements to technological progress, aeronautical biofuels.

[0009] In order to improve the market entry acceptability of new aircraft, particularly electric turboprop aircraft, phase synchronization ("synchrophasing") of the aircraft's propellers is planned to reduce the noise felt inside the aircraft. This is to ensure that the noise signature of these new electric turboprop aircraft does not exceed that of aircraft already on the market. In practice, this typically involves achieving, by phase synchronization between the propellers, a noise reduction compared to current thermal turboprops of around 25 dB for a usual noise level felt inside the aircraft that can range from 85 dB to 100 dB.

[0010] As is known, phase synchronization between propellers involves measuring the rotation speed of the aircraft's propellers, which then allows the speed and rotation angle of these propellers to be synchronized. This measurement is usually carried out using inductive or Hall effect sensors. However, in the case of propellers driven by medium to high power electric thrusters, in addition to the already restrictive environment of the sensors, particularly in terms of vibration and thermal conditions, there are electromagnetic disturbances associated with the electrical power of the thrusters. The sensors usually used have too low an electromagnetic susceptibility, which degrades the accuracy of their measurements.

[0011] It is therefore desirable to have a device for measuring the rotation speed of the propellers which is responsive and precise and which is not very sensitive to electromagnetic disturbances. Description of the invention

[0012] To this end, the invention is the result of technological research aimed at significantly improving the performance of aircraft, and in this sense, contributes to reducing the environmental impact of aircraft. For this purpose, the invention relates to a device for measuring the rotation speed of an aircraft propeller comprising:

[0013] - an optical speed sensor;

[0014] - an optical fiber connected to the optical speed sensor and intended to be connected to an aircraft control unit; and

[0015] - at least one target configured to track the rotation of the propeller, the optical speed sensor being configured to detect the target.

[0016] The optical fiber is completely immune to electromagnetic interference, as is the optical speed sensor. This allows for a device for measuring the rotation speed of a propeller that is completely insensitive to its electromagnetic environment, particularly to interference from electrical cables or converters using power electronics. Thanks to this propeller speed measurement, the aircraft control system will be able to accurately and consistently check whether the propeller has the same speed as the other propellers.

[0017] According to a particular characteristic of the invention, the optical speed sensor is fixed to a fixed part of a motor driving said propeller.

[0018] For example, it is fixed to the fixed structure supporting the engine. This allows the optical speed sensor to be less subject to vibrations from the propeller and the engine.

[0019] According to another particular characteristic of the invention, the optical fiber is placed along a wing of the aircraft comprising said propeller.

[0020] For example, it can be run along the leading edge of the wing. This advantageously reduces the length of optical fiber required, as it allows the optical speed sensor and the aircraft control unit to be connected via the shortest route. Furthermore, it also allows the passage of the optical fiber to the aircraft control unit using existing electrical cables or strands connecting the power supplies (converters) to the electric propulsion motors. A thermal protection sheath for the fiber will then be advantageously provided. This protects the optical fiber from high temperatures, particularly those generated by high-voltage power cables when the fiber runs along the leading edge of the wing. This thermal protection is, for example, made of a polymer, such as polytetrafluoroethylene (PTFE).

[0021] The optical fiber can also be routed along the wing's trailing edge. This allows the optical fiber to be routed in an unobstructed area of ​​the wing. Furthermore, by running along the trailing edge, the optical fiber is then sufficiently far from the power supply cables, which can be subject to significant self-heating, making it possible to dispense with the thermal protection layer.

[0022] According to one embodiment of the invention, the target is placed on a shaft of the motor driving said propeller or on a shaft carrying said propeller, and the optical speed sensor is placed on a radial axis, perpendicular to the axis of rotation of the shaft of the motor or of the shaft carrying said propeller.

[0023] By placing the target on the motor shaft or the propeller shaft, radial measurements can be made to determine the rotational speed of the propeller. This arrangement allows the optical sensor to be integrated as close as possible to the moving part carrying the measurement targets. This proximity guarantees minimal mechanical play between the fixed part carrying the sensor and the moving part carrying the targets. In other words, this guarantees minimal relative displacements due to vibration phenomena, between the moving part and the sensor making the measurement. The accuracy of the measurement and its invariance relative to vibration conditions are thus improved.

[0024] According to another embodiment of the invention, the target is placed on a flange fixed to the shaft of the motor driving said propeller or to the shaft carrying said propeller, and the optical speed sensor is opposite the flange in a direction parallel to the axis of rotation of the shaft of the motor or of the shaft carrying said propeller. By placing the target on a part rotating with the propeller, axial measurements of the rotation speed of the propeller are made.

[0025] According to a particular characteristic of the invention, the target is a shape and / or a color contrast and / or a hole.

[0026] The target may, for example, be a particular shape appearing on the motor shaft, the shaft carrying the propeller, or the flange attached to one of these two shafts. For example, the shaft or the flange may be serrated and the target may be formed by a tooth or a hollow between two teeth, or by a hole present on the shaft or the flange.

[0027] Furthermore, the target can also be a colored spot or a contrast with the background color present on a tree or the flask, the colored spot being able, for example, to be formed by white paint and / or reflective paint.

[0028] The target can also be formed by a colored mark or shape, which will improve its detection by the optical sensor. It can, for example, be formed by a white-painted tooth present on the motor shaft, or the shaft carrying the propeller or even the flange, the shafts and the flange being in this case dark in color.

[0029] According to a particular characteristic of the invention, the device comprises a plurality of targets and the optical speed sensor is configured to detect the plurality of targets.

[0030] Having multiple targets can improve the accuracy of speed measurement. Additionally, the targets can all be identical, or different targets can be chosen. In another aspect, the targets can be equidistant from each other or not. Having different and / or unequally spaced targets can help detect the direction of rotation of the propeller, in addition to measuring the rotational speed.

[0031] According to another particular characteristic of the invention, the distance between the target or targets and the optical speed sensor is between 1 mm and 10 mm. Another subject of the invention is an aircraft comprising a plurality of propellers, in which each propeller comprises a measuring device according to the invention.

[0032] Thus, in this aircraft, each propeller of the aircraft comprises a measuring device according to the invention. In addition, all the devices can be identical or different. For example, one can choose to pass the optical fibers along the leading edge for the propellers present on one wing and along the trailing edge for the propellers present on the other wing. One can also place, for certain propellers, the optical speed sensors axially opposite a flange fixed on the engine shafts or the shafts carrying these propellers and for the other propellers, the optical speed sensors are placed on an axis radial to the axis of rotation of the engine shafts and the shafts carrying these other propellers. One can also vary the number of targets between the different propellers, and / or the type of targets and / or the distances between the targets of the same propeller, etc.

[0033] Brief description of the drawings

[0034] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not limiting in nature.

[0035] [Fig. IA] Figure IA represents, schematically and partially, an aircraft wing comprising three propellers whose rotation speed is measured by a measuring device according to one embodiment of the invention.

[0036] [Fig. IB] Figure IB shows, schematically and partially, a zoom on the aircraft wing, in particular on one of the turboprops associated with one of the propellers in Figure IA.

[0037] [Fig. 2A] Figure 2A shows, schematically and partially, a device for measuring the rotation speed of a propeller according to another embodiment of the invention.

[0038] [Fig. 2B] Figure 2B shows, schematically and partially, the targets of the measuring device of Figure 2A. [Fig. 3] Figure 3 shows, schematically and partially, a device for measuring the rotational speed of a propeller according to another embodiment of the invention.

[0039] Description of the embodiments

[0040] The invention is described below in the particular context of aircraft comprising electric thrusters. An electric thruster designates the assembly composed of a propeller and an electric motor driving this propeller.

[0041] Figures 1A and 1B represent, schematically and partially, an aircraft wing 140 comprising three propellers 110, 112, 114 each associated with a respective electric motor 111, 113, 115, and the rotation speed of each can be advantageously measured by a measuring device as will be described below.

[0042] The device for measuring the rotational speed of a propeller, such as the propeller 110, 112 or 114, comprises an optical speed sensor, an optical fiber 130 connected to the optical speed sensor and to a control unit 160 of the aircraft and at least one target configured to follow the rotation of the propeller in question. The optical speed sensor is configured to detect the target(s). The control unit 160 may comprise an optical signal converter into a digital logic signal to interpret the measurements of the optical speed sensor. Since the optical fiber is immune to electromagnetic interference, the optical signal is transported without interference from the optical speed sensor to the control unit 160. This contributes to the accuracy of the measurement of the rotational speed of the propeller in question.

[0043] With reference to Figure 1B, the optical fiber 130 is, in this exemplary embodiment, placed along the leading edge BA of the wing 140 which includes the propeller in question, the propeller 110 for example. This makes it possible to reduce the length of the optical fiber 130, because it is placed as close as possible to the speed sensor and passes through the shortest path between the speed sensor and the control unit 160. A thermal protection layer may surround this optical fiber 130 in particular to protect it from the heat generated by the high-voltage power cables generally passing along the leading edge BA of the wing 140, and which supply the electric motor of the propeller 110. The thermal protection may be made of a polymer material, for example PTFE.

[0044] Alternatively, it is possible to choose to run the optical fiber 130 along the trailing edge BF of the wing 140 if it is desired to reduce the size of the ancillaries (such as for example the high-power power cables, the propeller feathering actuators, the servomotors, etc.) running along the leading edge BA or if it is desired to avoid putting thermal protection on the optical fiber 130.

[0045] The device for measuring the rotational speed of the propellers 110, 112 and 114, in particular the optical speed sensor and the targets, is described in more detail in the remainder of the description with reference to FIGS. 2A, 2B and 3.

[0046] Figure 2A shows, schematically and partially, a device 210 for measuring the rotational speed of a propeller, represented by the propeller 211 in Figure 2A, according to an embodiment of the invention, which has the aerodynamic advantage of having no effect on the drag of the aircraft. Figure 2B shows the three targets 251, 252 and 253 of the device 210 of Figure 2A.

[0047] As shown with reference to Figures 1A and 1B, the measuring device 210 comprises an optical speed sensor 220, an optical fiber 230 connected to the optical speed sensor 220 and to a control unit of the aircraft, as well as at least one target 251, 252, 253 configured to track the rotation of the propeller 211. In this example, the device 210 comprises three targets 251, 252, 253 (the third target is not visible in Figure 2A, but is visible in Figure 2B) which are placed equidistant from each other. The optical speed sensor 220 is therefore configured to detect these three targets 251, 252, 253.

[0048] The targets 251, 252, 253 are placed on a flange 250 fixed to the shaft 270 carrying the propeller 211. In this example, they are formed by a color contrast on the flange 250. If the flange 250 is dark in color, for example black or dark gray, the targets 251, 252, 253 are light in color, for example white. Or on the contrary, if the flange 250 is light in color, the targets 251, 252, 253 can be dark in color. The contrast between the targets to be detected and the background can be increased by the use of a reflective or, on the contrary, absorbent paint for the targets.

[0049] The optical speed sensor 220 is fixed to a fixed part of the engine actuating the propeller 211, and more particularly, it is placed opposite the flange 250 in a direction X' parallel to the axis of rotation X of the shaft 270 carrying the propeller 211. The axial installation of the speed sensor 220 relative to the longitudinal axis of the engine (axis X), in an integrated and profiled manner in the casing of the propulsion engine of the propeller 211, makes it possible not to disturb the drag of the machine on the aerodynamic level.

[0050] In this example, the targets 251, 252, 253 are present on a flange 250 fixed to the shaft 270 carrying the propeller 211, but they may, instead, be present on another flange or another part fixed to the shaft of the motor actuating the propeller 211, such as for example a flange having a large diameter. If this is the case, the optical speed sensor 220 will be opposite this new flange or this new part in a direction parallel to the axis of rotation of the motor shaft.

[0051] Figure 3 shows, schematically and partially, a device 310 for measuring the rotation speed of a propeller according to another embodiment of the invention.

[0052] As in the first embodiment which has just been described, the measuring device 310 comprises an optical speed sensor 320, an optical fiber (not shown in FIG. 3) connected to the optical speed sensor 320 and to a control unit of the aircraft as well as at least one target 351, 352, 361, 362, 371, 372 configured to follow the rotation of the propeller.

[0053] In this second embodiment and as will be described, the sensor and the associated targets are more integrated into the internal part of the motor, which is more favorable to guaranteeing minimal mechanical play, which in a vibratory environment makes it possible to minimize the relative displacement between the fixed sensor and the mobile member rotating with the propeller, carrying the targets. The accuracy of the measurement and its invariance relative to the vibratory conditions are improved. In more detail, the optical speed sensor 320 is fixed to a fixed part of the motor actuating the propeller. More particularly, it is fixed in this example, to a fixed structure supporting or surrounding the motor, and it is placed on a radial axis XR to the axis of rotation X of the shaft and its flange 370.In order to measure the rotational speed of the propeller, the optical speed sensor 320 is also configured to detect at least one of the target groups (351, 352), (361, 362), and (371, 372).

[0054] The targets are placed on a member of the engine actuating the propeller, which is movable in rotation with the propeller, in the example illustrated, a front flange 370 of the motor shaft and more precisely on the edge of this movable member. These targets can be of several types: the targets 351, 352 and 371, 372 are bumps or prominences formed on the edge of the movable member, in particular, the targets 371, 372 also have a color contrast compared to the targets 351 and 352; and the targets 361, 362 are holes, in particular hollow shapes formed on the edge of the movable member. If the sensor 320 is configured to detect several groups of these targets (351, 352), (361, 362), and (371, 372), it will also be able to determine the direction of rotation of the propeller if, for example, the groups of targets are of different contrast or if the targets are not placed equidistantly.

[0055] In this example, the targets 351, 352, 361, 362, 371, 372 were present on the front flange 370 of the motor shaft driving the propeller. Alternatively, the targets could be present on the shaft of the motor driving the propeller. If so, the optical speed sensor 320 will be placed on an axis radial to the axis of rotation of the motor shaft.

[0056] For the two embodiments described with reference to figures 2 and 3, the optical fiber passes along the wing to the propeller whose rotation speed is to be measured, along the leading edge or along the trailing edge.

[0057] If the wing, or more generally the aircraft, comprises several propellers, at least two propellers, whose rotation speeds are to be measured, it will be possible to place as many devices according to the invention as there are propellers. The optical fibers of each of these devices may all pass along the leading edges or along the trailing edges of the wings of the aircraft, or may even be distributed between the two edges of the wings of the aircraft in order to optimize the space requirement in the wings.

[0058] As with the targets present in each of these devices, their number may vary between the devices, as may their shape or location. Whatever the embodiment, if several targets are present in the measuring device, they may be equidistant from each other or placed at varying distances, if the aim is also to determine the direction of rotation of the propeller.

[0059] Regardless of the embodiment, the distance between a target and the optical speed sensor is between 1 mm and 10 mm.

[0060] Regardless of the embodiment, the optical speed sensor is an optical sensor with sub-degree accuracy. For example, it is a slotted or circular sensor.

Claims

Claims

1. Device (210, 310) for measuring a rotation speed of an aircraft propeller (110, 112, 114, 211) comprising: - an optical speed sensor (220, 320); - an optical fiber (130, 230) connected to the optical speed sensor and intended to be connected to a control unit (160) of the aircraft; and - at least one target (251, 252, 253, 351, 352, 361, 362, 371, 372) configured to track the rotation of the propeller (110, 211), the optical speed sensor being configured to detect the target.

2. A measuring device according to claim 1, wherein the optical speed sensor is fixed to a fixed part of a motor driving said propeller.

3. A measuring device according to any one of claims 1 or 2, wherein the optical fiber (130) is placed along a wing (140) of the aircraft comprising said propeller (110).

4. A measuring device according to any one of claims 1 to 3, wherein a thermal protection layer surrounds the optical fiber.

5. Measuring device (310) according to any one of claims 1 to 4, wherein the target (351, 352, 361, 362, 371, 372) is placed on a front flange (370) of the shaft of the motor driving said propeller or on a shaft carrying said propeller, and the optical speed sensor is placed on a radial axis (XR) perpendicular to the axis of rotation (X) of the shaft of the motor or of the shaft carrying said propeller.

6. Measuring device (210) according to any one of claims 1 to 4, in which the target (251, 252, 253) is placed on a flange (250) fixed to the shaft of the motor actuating said propeller or to the shaft (270) carrying said propeller, and the optical speed sensor (220) is opposite the flange in a direction parallel (X') to the axis of rotation (X) of the shaft of the motor or of the shaft carrying said propeller.

7. A measuring device according to any one of claims 1 to 6, wherein the target is a shape and / or a color contrast and / or a hole.

8. A measuring device according to any one of claims 1 to 7, comprising a plurality of targets and the optical speed sensor being configured to detect the plurality of targets.

9. An aircraft comprising a plurality of propellers, wherein each propeller comprises a measuring device according to any one of claims 1 to 8.

Images