Hydraulic torque measuring device for an aircraft engine unit

Abstract

The invention relates to a hydraulic torque measuring device for an aircraft engine unit, comprising: a hermetically sealed housing (20a) comprising a rigid wall (21) and a deformable wall (22), the rigid wall and the deformable wall defining an internal volume (26); and at least one pressure measuring element (28) capable of measuring the pressure in the internal volume (26), the hydraulic device (20) allowing an operating state in which the internal volume (26) is filled only with an incompressible liquid and the deformable wall (22) is configured to withstand pressure. The invention also relates to a gearbox comprising such a hydraulic device.

Description

Technical Field

[0001] This invention relates to a hydraulic torque meter, particularly for use in aircraft engines. Background Technology

[0002] The technical background specifically includes documents US 3587304 A1 and US 5337612 A1.

[0003] In the aerospace field, known hydraulic torque meters rely on automatic hydraulic regulating mechanisms for torque measurement. The hydraulic pressure regulated by these mechanisms is a simple function of the torque transmitted by the associated engine. The axial thrust on one or more intermediate sprockets (e.g., helical teeth) of the reducer is proportional to the torque transmitted through that reducer. Sensors measure this regulated hydraulic pressure, and taking into account some conformational coefficients determined during engine acceptance testing, a calculator infers the actual torque transmitted by the engine from this pressure measurement.

[0004] refer to Figure 1 , Figure 2A , Figure 2B and Figure 3 A known hydraulic torque meter 320 implemented in a gearbox 300 of a helicopter engine unit (not shown) is described.

[0005] exist Figure 1 On the gearbox 300, the cover 3210 of the hydraulic piston 321 (described below) and the pump filter support block (also described below) that carries the pressure sensor 328 can be seen. The cross-section of the gearbox 300 is... Figure 2B The gearbox 300 is shown in detail below. It has a housing 304 and a sprocket 306, which is rotatably mounted in the housing 304. The shaft 306a of the sprocket 306 is pivotally connected to the hydraulic piston 321 of the torque meter 320 via a bearing 308. The axial thrust applied to the piston 321 by the sprocket 306 has the function of adjusting the opening of the valve 322, that is, adjusting the degree of oil leakage in the supply circuit 323 supplied from the pump 324. Figure 2A and Figure 2B Therefore, a balance is achieved between the axial thrust applied by the sprocket 306 and the thrust of the hydraulic fluid on the piston 321. This is achieved via pressure sensor 328. Figure 1 , Figure 2A , Figure 3 The pressure regulated in the supply circuit 323 is measured. Sensor 328 here consists of a hydraulic piston 3280 and a resistive element 3281. The pressure F applied to the hydraulic piston 3280 by the fluid is converted into an output signal in 3281, which in this case is a voltage proportional to the fluid pressure. Electrical connector 3282 ( Figure 3It allows the output signal to be transmitted to the computing unit 329, which controls the visual indicator 330 in the aircraft cabin.

[0006] Another hydraulic torque meter is known from document FR3025602. In this device, a rod 30 can be translated longitudinally under the action of an axial thrust 31 representing the torque to be measured. A hydraulic circuit 40 is provided in which fluid 38 circulates. The torque meter also includes a pressure measuring bladder 46, which includes a pressure chamber 36 supplied with fluid from the hydraulic circuit 40. A flexible sealing diaphragm 32 is in contact with the fluid in the pressure chamber 36, extends in a plane substantially perpendicular to the rod 30, and is firmly attached to one end of the rod 30 such that longitudinal displacement of the rod 30 causes deformation of the diaphragm 32. The device also includes a leakage port 44 for the fluid 38 from the pressure chamber 36, and a valve 48 configured to adjust the pressure of the fluid 38 in the pressure chamber 36 according to the deformation of the diaphragm 32.

[0007] In this type of torque meter, hydraulic pressure regulation is also provided by a continuous and excess hydraulic chamber supplied from the engine's lubricating oil circuit. A valve restricts the outflow from the hydraulic chamber, which automatically regulates the pressure until it fully compensates for the axial thrust of the intermediate sprocket.

[0008] Such regulating devices can be used in a wide variety of forms on different engines and can be improved. Their basic characteristics (especially the valve opening-flow rate-pressure differential relationship) are not yet known experimentally, and their sensitivity to manufacturing tolerances must be determined on a case-by-case basis.

[0009] Because these systems rely on establishing a steady state (which depends on the engine oil circuit performance), it is impossible to accurately measure the torque during the engine's rapid transient states. In particular, the measurement of the maximum torque reached during transient states is uncertain, which may lead to exceeding the engine's permissible torque without being detected by the engine's regulation and monitoring systems.

[0010] This type of system also represents the energy loss collected from the lubrication circuit.

[0011] The current system acts as the axial abutment of the intermediate sprocket, but only in one direction. A second axial abutment must be added in the other direction.

[0012] This invention aims to overcome the shortcomings of known solutions and proposes a simple, effective, and economical solution to the problem. In particular, this invention aims to simplify existing solutions and improve the reliability and efficiency of torque measurement. Summary of the Invention

[0013] Therefore, the present invention relates to a hydraulic torque measuring device for a gearbox in an aircraft engine unit, the gearbox including at least one sprocket having a shaft extending along a longitudinal axis, the hydraulic device comprising:

[0014] - A housing comprising rigid walls and deformable walls defining an internal volume, the deformable walls being configured to be pivotally connected to a sprocket shaft, and

[0015] - At least one pressure measuring element, the at least one pressure measuring element being adapted to measure the pressure in the internal volume.

[0016] The hydraulic device operates in a state where its internal volume is filled only with incompressible fluid and its deformable walls are configured to withstand pressure. In this hydraulic torque measuring device, the housing is hermetically sealed.

[0017] The hydraulic torque measuring device according to the invention may include one or more of the following features, either independently or in combination with each other:

[0018] - The deformable wall is a metal bellows;

[0019] - The metal bellows is cylindrical in shape and is deformable along its axial dimension;

[0020] - The hydraulic unit also includes a torque calculation device configured to calculate torque based on the pressure measured by a pressure measuring element in the internal volume.

[0021] The present invention also relates to a gearbox for an aircraft engine unit, the gearbox including the aforementioned hydraulic torque measuring device, the gearbox including at least one sprocket having a shaft extending along a longitudinal axis, the deformable wall being pivotally connected to the shaft.

[0022] The gearbox according to the invention may include one or more of the following features, which may be considered independently or in combination with each other:

[0023] - The deformable wall is a cylindrical deformable metal bellows that extends coaxially with the longitudinal axis of the sprocket shaft.

[0024] - Rigid walls form an integral part of the gearbox housing;

[0025] - The rigid wall includes filling and / or clearing channels that are closed when the hydraulic device is in operation.

[0026] - The rigid wall includes a pressure measurement interface, and the pressure measurement element is connected to the internal volume through the pressure measurement interface;

[0027] - The gearbox is the helicopter's main gearbox. Attached Figure Description

[0028] Further features and advantages of the invention will become apparent from the following detailed description, in which reference is made to the accompanying drawings, in which:

[0029] - Figure 1 This is a perspective view of a gearbox for an aircraft engine unit based on existing technology, which has a torque meter equipped with a pressure sensor;

[0030] - Figure 2A schematically shown Figure 1 The embodiment of the torque meter in the gearbox, and here is a cross-section of the gearbox;

[0031] - Figure 2B yes Figure 1 and Figure 2A An enlarged view of the cross-sectional view of the gearbox in the image;

[0032] - Figure 3 yes Figure 1 A perspective view of the pressure sensor in the image; and

[0033] - Figure 4 This is a cross-sectional view of a gearbox equipped with a torque meter according to the present invention. Detailed Implementation

[0034] In the following description, the invention applies to gearbox 3, such as the main gearbox of a helicopter engine unit (not shown). However, the gearbox is not limited to this type of engine unit and can be applied to other types of engine units and other types of aircraft, especially when torque needs to be measured.

[0035] The gearbox 3 includes a rigid housing 4 and a set of sprockets 5. The set of sprockets 5 includes at least one first sprocket 6 and a second sprocket 7, which mesh with each other at positions 6a and 7a, respectively. This set of sprockets 5 belongs to a reducer of the gearbox 3 (not shown in detail). Sprocket 6 is, for example, but not exclusively, the intermediate sprocket of this reducer.

[0036] The sprocket 6 extends approximately around the longitudinal axis A and is rotatable about this longitudinal axis. The teeth 6a of the sprocket 6 are evenly distributed around the longitudinal axis A.

[0037] In the example shown, the sprocket 6 includes a shaft 6b, and the sprocket 6 is configured to rotate about the shaft 6b. The shaft 6b is a hollow shaft and has a series of hollow cylindrical segments 6b1, 6b2, 6b3, each of which has a decreasing diameter toward the hydraulic torque meter 20 described below.

[0038] The web 6c extends here from the end of the cylindrical section 6b1 adjacent to the cylindrical section 6b2. The web 6b carries a cylindrical toothed ring 6d provided with teeth 6a. The distal end 6e extends to the end of the cylindrical section 6b3.

[0039] The housing 4 includes multiple walls, of which only two, 10 and 11, are shown here. Wall 11 defines an internal volume 12 in which the end 6e of the sprocket 6 and the cylindrical segments 6b2 and 6b3 are housed. Thus, the sprocket 6 is rotatably mounted in the housing 4 via a bearing 8. In this example, the bearing 8 is not limited to a rolling bearing.

[0040] As described above, the gearbox 3 also includes a hydraulic torque measuring device 20, also known as a hydraulic torque meter. The torque meter 20 is designed to measure the axial thrust of one of the multiple sprockets in the set of sprockets 5, for example, during the engine starting phase or in a stable state. Here, the torque meter 20 is a generally elongated element aligned with the aforementioned longitudinal axis A, that is, coaxial with the axis on which the sprocket 6 is centered.

[0041] The hydraulic torque meter 20 has a housing 20a, which includes a rigid wall 21 and a deformable wall 22. As will become clear from the following text, the housing 20a is hermetically sealed.

[0042] Walls 21 and 22 define the hydraulic chamber 26 between them. When the hydraulic torque meter 20 is in operation, the hydraulic chamber 26 is (only) filled with an incompressible fluid, such as engine oil.

[0043] The deformable wall 22 is a metal bellows. The deformable wall 22 is generally cylindrical in shape. In the operating state of the torque meter 20, the deformable wall 22 is configured to be coaxial with the longitudinal axis A of the shaft 6b. The deformable wall 22 has low axial stiffness around its rest position. The rest position of the deformable wall 22 is defined such that no axial pressure directly related to the movement of rotating elements (e.g., sprocket 6) is applied to the deformable wall.

[0044] The deformable wall 22 includes a first end portion 23, a central portion 24, and a second end portion 25.

[0045] The first end portion 23 includes, but is not limited to, an annular flange 230, which is used to ensure that the torque meter 20 is installed in the gearbox 3.

[0046] The central portion 24 forms the main body of the metal bellows itself. The central portion 24 has a generally cylindrical shape. It is manifested as a series of folds in the metal sheet itself. The term "fold" should be understood as referring to a layer compared to an adjacent fold or layer. The number of folds can be selected in a non-limiting manner between 2 and 20, preferably between 4 and 12.

[0047] The second end portion 25 forms a connection device with the shaft 6b of the sprocket 6, and includes a plate 250, a sleeve 253, an attachment ring 254, and a bearing 255.

[0048] Plate 250 is disc-shaped. Plate 250 is provided with pin 251. Plate 250 is mounted on the end of the central portion 24 opposite to the first end portion 23. Pin 251 protrudes from the center of the disc formed by plate 250 on the surface of the plate opposite to the central portion 24. Pin 252 has threads 252 on its outer cylindrical surface.

[0049] The socket 253 is a cylindrical element. The socket 253 has a generally H-shaped cross-section that defines two opposing cavities. The socket 253 has an internal thread in one of the cavities. This internal thread allows the socket to be screwed onto the pin 251 for attachment to the pin 251.

[0050] Furthermore, the sleeve 253 is rotatably mounted in the end 6e of the sprocket 6 and in the cylindrical section 6b3 via a bearing 255 (here, a ball bearing) and an attachment ring 254.

[0051] The torque meter 20 is also installed in the gearbox 3 as follows.

[0052] In the non-limiting example shown, the rigid wall 21 is an integral part of the aforementioned outer casing 4. In other words, the wall 21 serves as a cover for the outer casing 4, enclosing the internal volume 12.

[0053] Wall 21 is preferably attached to wall 11 by a threaded connection, rather than being restrictedly attached to wall 11. Wall 11 and wall 21 clamp (i.e., tighten) the annular flange 230 between them. Thus, the annular flange 230 is sealed between wall 11 and wall 21 of housing 4.

[0054] Therefore, apart from being rotatably mounted at the second end portion 25 of the deformable wall relative to the end 6e of the sprocket 6, the deformable wall 22 is attached to the housing 4 at its first end 23.

[0055] A groove 271 for accommodating the O-ring 270 is provided in the end plane B of the wall 11, and the annular flange 230 contacts this end plane when the torque meter 20 is assembled. Therefore, a seal for fluid is ensured between the wall 11 and the annular flange 230.

[0056] In the above configuration, it can be seen that the sprocket 6 is pivotally mounted in the housing 4 via the bearing 8. The sprocket 6 is also pivotally connected to the bellows 22. Specifically, the second end portion 25 of the bellows 22 is pivotally connected to the shaft 6b via the bearing 255. In other words, the rotation of the sprocket 6 does not drive the bellows 22 to rotate. However, any axial pressure along axis A, whether negative or positive, i.e., along... Figure 4 Axial pressure in any orientation along axis A will be reflected on bellows 22 along axis A and will tend to change the fluid pressure in hydraulic chamber 26. Torque meter 20 thus forms the axial contact portion of sprocket 6.

[0057] Here, the wall 21 is passed through the first pipe 210, and when the torque meter 20 and / or the gearbox 3 are in operation, the first pipe 210 is sealed by the plug 2100.

[0058] The conduit 210 forms a filling and emptying conduit. The plug 211 is configured to close the conduit 210 when the torque meter 20 is in operation.

[0059] The wall 21 is also penetrated by a second conduit 220. The conduit 220 forms a pressure measuring interface. In other words, the conduit 220 is in fluid communication with a pressure measuring device (not shown).

[0060] The torque meter includes at least one pressure measuring element 28 of the type of pressure sensor. The pressure measuring element 28 is connected to the hydraulic chamber 26 via a conduit 220. The purpose of the pressure measuring element 28 is to measure the pressure and pressure changes in the hydraulic chamber 26.

[0061] Alternatively, the torque meter 20 has a second pressure measuring element. This is advantageous, for example, in the face of failure of the first or second pressure measuring element and / or for having redundant pressure measurements to improve measurement reliability. A pressure measuring interface can then be provided to communicate with both pressure measuring elements. Alternatively, not shown, a pressure measuring interface is provided for each pressure measuring element via a rigid wall 21.

[0062] The torque meter also includes a torque calculation device 29, which is configured to calculate the engine torque based on the pressure measured in the internal volume by at least one pressure measuring element 28. Where appropriate, the measured torque can be displayed on an indicator 30, for example, in the aircraft cabin.

[0063] The term "airtight seal" means that housing 20a has no continuous supply of incompressible fluid and no discharge circuit for that fluid. In other words, the hydraulic chamber 26, defined by walls 21 and 22, is filled with incompressible fluid during the preparation operation of torque meter 20 (e.g., initial purging and filling operation of hydraulic chamber 26, or subsequent maintenance operation of torque meter 20), but is not penetrated by incompressible fluid flow during the operating state of hydraulic torque meter 20.

[0064] The aforementioned hydraulic torque meter 20 can be advantageously implemented in the gearbox of an aircraft (such as a helicopter or airplane).

[0065] This invention offers the following advantages. The proposed solution eliminates the limitations of existing automatic pressure regulation systems, thereby eliminating:

[0066] • The engine oil supply circuit needs to be obtained from the general lubrication circuit;

[0067] • Associated regulating valve.

[0068] Therefore, the main contribution of this solution is that it greatly simplifies the known hydraulic torque meters that have various advantages.

[0069] Therefore, the hydraulic torque meter 20 offers greater reliability. Torque measurement becomes instantaneous and is now independent of engine conditions. There is no longer a need to wait for the lubrication circuit to reach a balanced state, which is partly dependent on the engine. Thus, torque is measured with the same accuracy in transient conditions as in steady-state conditions.

[0070] This device provides bidirectional axial contact for sprocket 6. Negative torque can be measured if necessary.

[0071] The metal bellows 22 will be selected to have sufficient axial flexibility to avoid a significant increase in the internal pressure of the hydraulic chamber 26 due to the thermal expansion of the fluid filling the hydraulic chamber 26. The metal bellows 22 will also be selected to be sufficiently robust in the radial direction to withstand the internal pressure of the fluid under high torque (up to 10 bar) and its repeated cycles (fatigue design).

[0072] Advantageously, the pressure measuring element 28 can be selected as both a pressure sensor and a temperature sensor (not shown) to allow for consideration of pressure increases caused by the thermal expansion of the liquid. The thermal component of the pressure measurement can then be eliminated by software.

[0073] Advantageously, in order to allow for perfect clearance of the hydraulic chamber 26, the housing pressure sensor assembly can be assembled and pre-filled and cleared in the workshop, and consists of the following components:

[0074] • The shell 20a that has been cleared and filled;

[0075] • Pressure sensor 28.

[0076] Therefore, components 20a and 28, which form the axial contact portion of the sprocket 6 mounted in the gearbox 3, can be replaced without disassembling the reducer. This allows for significant time savings during maintenance operations.

[0077] The filling and clearing pipe 210 allows any air bubbles to be removed when filling the hydraulic chamber 26.

Claims

1. A hydraulic torque measuring device (20) for a gearbox in an aircraft engine unit, the gearbox including at least one sprocket having a shaft extending along a longitudinal axis, the hydraulic torque measuring device comprising: - A housing (20a) comprising a rigid wall (21) and a deformable wall (22) defining an internal volume (26), the deformable wall being configured to be pivotally connected to the shaft of the sprocket, and - At least one pressure measuring element (28), said at least one pressure measuring element being adapted to measure the pressure in the internal volume (26), The hydraulic torque measuring device (20) allows for the following operating state: in this operating state, the internal volume (26) is filled only with incompressible liquid and the deformable wall (22) is configured to withstand pressure. The characteristic feature is that the housing (20a) is airtightly sealed.

2. The hydraulic torque measuring device (20) according to claim 1, wherein, The deformable wall (22) is a metal bellows (23, 24, 25).

3. The hydraulic torque measuring device (20) according to claim 2, wherein the metal bellows is cylindrical in shape and is deformable along its axial dimension.

4. The hydraulic torque measuring device (20) according to any one of claims 1 to 3, further comprising a torque calculation device (29) configured to calculate torque based on pressure measured by the pressure measuring element (28) in the internal volume (26).

5. A gearbox (3) for an aircraft engine unit, the gearbox comprising a hydraulic torque measuring device (20) according to any one of claims 1 to 4, the gearbox comprising at least one sprocket (6) having a shaft (6b) extending along a longitudinal axis (A), the deformable wall (22) being pivotally connected to the shaft (6b).

6. The gearbox (3) according to claim 5, wherein, The deformable wall is a cylindrical deformable metal bellows and extends coaxially with the longitudinal axis (A) of the shaft (6b) of the sprocket (6).

7. The gearbox (3) according to claim 5 or 6, wherein, The rigid wall (21) forms an integral part of the outer shell (4) of the gearbox (3).

8. The gearbox (3) according to claim 5 or 6, wherein, The rigid wall (21) includes a filling and emptying conduit (210) which is closed when the hydraulic torque measuring device is in operation.

9. The gearbox (3) according to claim 5 or 6, wherein, The rigid wall (21) includes a pressure measurement interface (211), and the pressure measurement element (28) is connected to the internal volume (26) through the pressure measurement interface (211).

10. The gearbox (3) according to claim 5 or 6, wherein the gearbox is a helicopter main gearbox type.

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