TORQUE MEASUREMENT TO STRAIN

1. Technical Field of the Invention

A torque. In particular, the invention relates to a torque meter for measuring torque of a transmission element of a turbine engine of an aircraft.

2. BACKGROUND

The torque are torque measuring devices that exist in several forms depending on the application area, equipment with a torque is to be measured and the desired degree of accuracy. In the field of aeronautics, is frequently used hydraulic torque. These torque function for example through an intermediate helical gear, for which the applied torque causes a proportional axial thrust to the torque to be measured. This axial thrust is applied to a piston connected to the intermediate pinion. Another embodiment frequently encountered is the measurement of the axial thrust of a planetary gear, also proportional to the torque to be measured. More generally, any custom helical gear is possible.

The movement of the piston as a function of measured torque causes pressure on the oil in a measurement chamber fed by a hydraulic circuit to balance the pressure exerted by the piston on the oil and fuel to the piston. Measuring the pressure in this equilibrium by a pressure sensor makes it possible to deduce the measured torque.

These hydraulic torque have the disadvantages of being sensitive to friction, due to the sealing elements and bearings, and leakage, due to aging of the sealing elements, the change in oil viscosity, temperature, etc. . Thus, the accuracy of the hydraulic torque is not assured and maintenance is regularly required. Moreover, it is impossible to measure a negative torque with such torque.

Other torque used are torsion torque, comparing the phase of the shaft subjected to torque with a rotating shaft but not subjected to torque. However, the accuracy of the torque measurement by the torsion torque

depends on the length of the shaft, which causes significant congestion of torsion torque for accurate measurement. In addition, not subject rotating shaft torque, which is the benchmark, a cost and an additional weight to the system.

3. Objectives of the invention

The invention aims to alleviate at least some of the disadvantages of known torque.

In particular, the invention also aims to provide, in at least one embodiment of the invention, a compact torque.

The invention also aims to provide, in at least one embodiment, a torque using no hydraulic elements requiring management tightness.

The invention also aims to provide, in at least one embodiment of the invention, a specific torque.

The invention also aims to provide, in at least one embodiment of the invention, a reliable torque, low maintenance.

The invention also aims to provide, in at least one embodiment, a torque meter adapted to measure a negative torque.

The invention also aims to provide, in at least one embodiment, a torque meter insensitive to temperature variations.

4. Summary of the Invention

To do this, the invention relates to a torque meter comprising a housing and a movable part mounted in translation in the housing along a longitudinal direction under the effect of an axial thrust representative of a torque to be measured, characterized in that comprises:

a bearing surface connected to the housing by at least one of its ends extending at least partially in a plane substantially perpendicular to the longitudinal plane, a longitudinal end of said movable member, said contact end being adapted to be brought into contact with said bearing surface so that a longitudinal displacement of the movable part causes a deformation

of the bearing surface,

means for measuring the deformation of the bearing surface.

A torque transducer according to the invention therefore makes it possible to measure the torque of a transmission element a transmission channel, for example a transmission shaft, without using a power or reference shaft or to the hydraulic elements. A movable part is displaced in translation according to the torque to be measured, and this moving part causes the deformation of a supporting surface. The deformation of the bearing surface is therefore representative of the torque, and the extent of this deformation makes it possible to determine the torque. The torque thus occupies a small footprint relative to a torque to twist and bulk substantially equivalent to or less than a hydraulic torque, without requiring a hydraulic circuit and therefore without requiring an associated seal. The

The supporting surface is directly or indirectly connected to the housing by one of its ends. One end of the bearing surface is for example one of the support surface edges. The contact end is preferably in contact with the support surface so that the deformation caused by the movement of the movable member is maximized, so as to improve the accuracy of strain measurement.

Advantageously, the deformation of the support surface is elastic deformation. Maintaining the deformation of the bearing surface in an elastic field provides the same torque measured for the same measured deformation.

Advantageously and according to the invention, the means for measuring deformation of the bearing surface include a proximity sensor, connected to the casing, facing the bearing surface, and configured to measure the displacement of the support surface in the longitudinal direction.

by moving the bearing surface is meant a modification of the position of at least a portion of the bearing surface.

According to this aspect of the invention, the displacement of the bearing surface in the longitudinal direction is due to the bending of the bearing surface in the longitudinal direction due to the displacement of the movable part. This movement is

representative of the torque to be measured. The proximity sensor, measuring the distance between itself and the bearing surface, so to measure this displacement corresponding to a variation of this distance.

Advantageously and according to the latter aspect of the invention, the proximity sensor may be an inductive proximity sensor.

According to this aspect of the invention, an inductive proximity sensor for measuring the displacement in good condition by reducing the risk measures disturbances due to the nature of the medium between the proximity sensor and the bearing surface. In particular, the measure is not disturbed in case of gases, particles, oil, etc. between the proximity sensor and the bearing surface, this presence being possible within the framework of the use of torque in a turbine engine. The inductive proximity sensor detects the distance to a metal object, the bearing surface must therefore, in this embodiment, be formed of metal or comprise at least a metal portion which is oriented toward the proximity sensor.

Advantageously, the proximity sensor is an inductive sensor with eddy currents.

Inductive proximity sensors, including eddy current sensor, have good accuracy and good reliability, allowing for accurate and reliable torque value measured.

Advantageously and according to the invention, the contact end and the bearing surface are integrally connected by a fastening.

According to this aspect of the invention, the attachment allows to make integral the bearing surface and the movable part, thus allowing the measurement of negative torque, whatever the measuring means used.

Advantageously, when the proximity sensor is an inductive sensor, the holder is metallic and is oriented toward the proximity sensor. The proximity sensor thus measures the distance between itself and the metal fixture to deduce the deformation of the bearing surface.

Advantageously and according to the invention, the means for measuring deformation of the bearing surface comprise at least one strain gauge arranged on the

support surface and adapted to measure a value representative of the deformation of the bearing surface.

According to this aspect of the invention, the deformation of the bearing surface being representative of the torque to be measured, a measure of this deformation makes it possible to determine the torque. To improve the accuracy and stability (including temperature) of measurement, or strain gauges may be connected to a Wheatstone bridge.

Advantageously, the strain measured by the strain gauges or is a deformation due to extension or compression of the bearing surface, due to a force exerted by the contact end of the movable part on the surface of 'support.

Advantageously and according to the invention, the bearing surface is connected to the housing via a support formed of a material not deformed according to changes in temperatures.

According to this aspect of the invention, the support serves to minimize the influence of temperature on the measurement of the deformation of the bearing surface, in particular when this measurement is obtained by using proximity sensor. The use of a separate carrier housing also allows easy maintenance, the support may be replaced, avoiding to replace the entire housing. Such a material does not deform according to the temperature variation is for example Invar.

Advantageously and according to the invention, the bearing surface is formed of a material whose Young's modulus is relatively insensitive to temperature variations.

According to this aspect of the invention, the deformation of the bearing surface measured by the means for measuring the deformation is not dependent on the temperature of the bearing surface. Such a material whose Young's modulus is relatively insensitive to temperature variations is e.g. elinvar. The Young's modulus thus varies within ± 1%, depending on the composition of the material used in the temperature range which is subject the torque.

Preferably, the bearing surface is formed of a material having the Young's modulus does not vary depending on the temperature in the temperature range which is subject the torque.

As part of the use of torque in a turbine engine, the temperature changes in the torque can be significant. Torque measurement must take into account these changes in temperatures here in reducing the effects of these variations.

Advantageously, a torsion meter according to the invention comprises means for measuring the temperature.

According to this aspect of the invention, measurement of temperature by means of temperature measurement allows to detect any temperature variations that can cause measurement variations in the torque. The torque value is then adjusted taking into account the measured temperature value.

As part of the use of torque in a turbine engine, the temperature changes in the torque can be significant. Torque measurement must take into account these changes in temperatures here in offsetting the effects of these changes.

The invention also relates to a turbine engine comprising a transmission element, characterized in that it comprises a torque meter according to the invention mechanically connected to the transmission member so as to be able to measure the torque applied to the transmission element.

The transmission element may be for example a shaft, a pinion with helical internal or external toothing, etc. The measured torque is the torque passing through the transmission which includes the transmission element.

The invention also relates to a torque meter and a gas turbine engine characterized in combination by all or some of the features mentioned above or below.

5. List of Figures

Other objects, features and advantages of the invention will appear on reading the following description given by way of non-limiting and which refers to the appended figures in which:

Figure 1 is a schematic sectional view of a torque according to one embodiment of the invention,

Figure 2 is a schematic sectional view of a torque according to a second embodiment,

Figure 3a is a schematic sectional view of a portion of a torque according to one embodiment of the invention, measuring a torque C to a temperature of 0 ° C,

Figure 3b is a schematic sectional view of a portion of a torque according to one embodiment of the invention, measuring a torque C to a temperature of 150 ° C and comprising a bearing surface sensitive to temperature and a housing insensitive to temperature variations,

Figure 3c is a schematic sectional view of a portion of a torque according to one embodiment of the invention, measuring a torque C to a temperature of 150 ° C and comprising a housing and a sensitive support surface to temperature variations,

Figure 4 is a schematic sectional view of a torque according to a third embodiment of the invention,

6. Description of an embodiment of the invention

The following achievements are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference is to the same embodiment, or that the specifications apply only to a single embodiment. Simple features of different embodiments may also be combined to provide other embodiments. In the figures, scales and proportions are not strictly complied with, for purposes of illustration and clarity.

Figures 1 and 2 schematically show a sectional torsion meter 10 according to a first and a second embodiment of the invention. Each transducer 10 includes a housing 12 in which can move a part 14 movable in translation. The displacement in translation of the mobile part 14 is carried along a longitudinal direction, here parallel with an axis 16 of the movable part. The views of Figures 1 to 4, the movable member 14 thus moves from top to bottom or from bottom to top. Each transducer 10 is advantageously used to measure the torque of a rotating shaft in a turbine engine of an aircraft.

The movable piece 14 is connected to a gear 18, with one or more helical teeth, through bearings 19. The torque applied to the pinion 18 transmits a thrust to the moving part 14, causing its movement. The translational movement of the movable piece 14 is therefore representative of the torque to be measured. The pinion 18 is connected to the housing 12 via bearings 20, the bearings 19 and bearings 20 for moving the moving part 14 and the pinion 18 in the longitudinal direction and the rotation about the axis 16 of the workpiece 14 mobile.

Each transducer includes a support surface 22, connected to the housing 12 by at least one of its ends and extending in a plane substantially perpendicular to the longitudinal direction plane. For example, the surface 22 of support may be an elongated plate whose length is greater than the other dimensions (thus equivalent to a beam), both ends of which are connected to the housing. The surface 22 of support can also be a membrane, in particular circular, every point on its periphery have been voted ends and are connected to the housing 12.

The surface 22 of support is in contact with one end of the moving part 14, said end 24 of contact. The displacement of the movable part 14 therefore causes a deformation of the surface 22 of support. In particular, the surface 22 of support being connected at one of its ends to the housing 12 and extending substantially perpendicularly to the longitudinal direction, the deformation of the surface 22 of support manifests itself in particular by a movement of the surface 22 of support and an extension or compression of the surface 22 of support. Deformation resembles a bending of the surface 22 supporting the ends of the surface 22 of support remaining fixed relative to the housing 12 and the portion of the surface 22 of support in contact with the

To measure this surface deformation bearing 22 and so determine the torque to be measured, the torque transducer 10 comprises means for measuring the deformation of surface 22 of support.

According to a first embodiment, shown in FIG 1, the means for measuring deformation of the surface 22 of support 26 comprises a sensor of proximity, otherwise called proximity meter for measuring the distance between itself and the surface 22 of 'support. Depending on the torque to be measured, this distance varies due to the displacement of the surface 22 of support in the longitudinal direction. Comparing the distance measured during the application of torque with the distance measured when no torque is applied to determine the displacement of the surface 22 of support. The torque meter 10 may further comprise an attachment 28 for integrally connecting the mobile part 14 to the surface 22 of support. In that case,

26 proximity sensor is advantageously a proximity inductive sensor type, because this type of sensor is not disturbed by the medium between the surface 22 and the support 26 of proximity sensor. In particular, when using the torque meter 10 in a turbine engine, the medium may comprise hot gas and oil. An inductive proximity sensor measures the distance between itself and a metal element: accordingly, either the surface 22 or the bearing portion of the surface 22 to which support 26 is oriented proximity sensor must be metal, or, if the torque transducer 10 comprises a fastening 28 of the surface 22 bearing the moving part 14, this attachment 28 may be metallic and 26 proximity sensor is then directed towards the attachment 28.

In practice, for example a torque meter used in a turbine engine, the distance between the proximity sensor 26 and the surface 22 of support (or the attachment 28) is less than 10mm. The surface of the moving support 22 difference between the minimum torque to be measured and the maximum torque to be measured is of the order of 0.3mm. The proximity sensors can measure commonly used on a 1mm gap with a sensitivity of about Ο, ΐμηι.

According to a second embodiment, shown in FIG 2, the means of the deformation of the surface 22 of support measures include at least one strain gauge 30, here two, for example, for measuring the deformation of the

surface 22 of support, including the deformation due to expansion or compression of the surface 22 of support caused by the movement of the mobile part 14.

A strain gauge, otherwise known as strain gauge, generally consists of a conducting part whose electrical resistance varies depending on the deformation of the workpiece. The part consists of a long bent electrical track forming a grid or coil. The variation of the electrical resistance of the conductive part is representative of the deformation of the strain gauge.

The sensor 26 proximate to the first embodiment and the gauges 30 or deformation of the second embodiment may be used alone or combined to allow for example a correlation of the results of the strain measurements and thereby improve the torque measurement.

Measuring the deformation of surface 22 of support is sensitive to the torque of the temperature variations 10. In particular, the surface 22 and bearing housing 12 may be deformed in the event of temperature variation, this deformation s 'adding to the deformations caused by the movable part 14. In addition, temperature variations may also affect the measurements obtained by the measurement means of the deformation. To overcome these problems, several options are possible. These options can be combined in particular.

One such option, which applies to all embodiments is added to torque 10 a means for measuring the temperature. The temperature is well known, and strain measurements can be corrected depending on the measured temperature.

Concerning the second embodiment shown in Figure 2, to reduce the effects of temperature variations on the gauges 30 of deformations, these are connected so that they form a Wheatstone bridge (not shown).

Figures 3a, 3b, and 3c schematically show in section a part of a torque meter 10 according to one embodiment, measuring a torque C, according to several temperature conditions. The torque 10 here takes the elements of

first embodiment.

3a shows the torque meter 10 measuring a torque C, and subjected to a temperature of 0 ° C. The mobile piece 14 exerts a force on the surface 22 of support, causing a deformation of the surface 22 of support. A proximity sensor 26 measuring this deformation by determining the distance represented by the double arrow 32, between itself and the bearing surface, or by fixing.

3b shows the torque meter 10 measuring the same pair C, and subjected to a temperature of 150 ° C. The housing 12 used on this torque is not sensitive to temperature variations, for example the distance represented by the double arrow 34 has not changed from the torque meter 10 of Figure 3a. A material which does not undergo deformation when the temperature varies, for example Invar, an alloy of iron and nickel (generally 64% iron and 36% nickel). The surface 22 of support is sensitive to temperature variations, and the surface 22 bearing deforms differently relative to the torque meter 10 shown in Figure 3a, subjected to a temperature of 0 ° C. The difference in distortion is mainly due to a variation in the rigidity of the surface 22 of support depending on the temperature. Here, the distance between the proximity sensor 26 and the surface 22 of support (or the attachment 28) is reduced, for the same torque C. Thus, the torque measurement must take into account the variation in the rigidity of the surface 22 bearing, for example by a temperature measurement to compensate for this variation.

It is also possible to use a housing 12 sensitive to temperature variations, as shown in Figure 3c. In addition, the housing 12 is also sized so that the temperature variations are calculated so that a defined torque, the distance measured by the proximity sensor 26 is the same regardless of the temperature: the expansion of the casing 12 in if temperature increase increases the distance between the proximity sensor 26 and the surface 22 of support (or fixation) so as to compensate the difference in deformation of the surface 22 of support due to the increase in temperature. As shown in FIG 3c, the distance represented by the double arrow 36 is the same as the distance 32 in Figure 3a, for the same torque measured by the torque C,

4 shows schematically in section a third embodiment of the torque meter 10, wherein the torque transducer 10 comprises a carrier 38 connecting surface 22 of support housing 12. In particular, the surface 22 of support 38 is connected to the support by means 40a, 40b of fasteners, and the support 38 is itself connected to housing 12 by means 42a, 42b fixing. 26 proximity sensor is arranged on the support 38. Only the lower portion of the torque meter 10 is shown.

To allow reduced sensitivity of the torque to temperature variations, the carrier 38 is formed of a material does not deform when the temperature variation, for example Invar, and the surface 22 of support is formed of a material whose Young's modulus varies little in the event of temperature variation, such as Elinvar, a nickel steel alloy (typically 36% nickel, 12% chromium). Thus, deformations of the surface 22 bearing measured by the means for measuring the deformation due to the displacement of the movable piece 14 are stable when the temperature at which the torque meter 10 is subjected vary.

CLAIMS

1. Torque comprising a housing (12) and a workpiece (14) mounted mobile in translation in the housing along a longitudinal direction under the effect of an axial thrust representative of a torque to be measured, characterized in that it comprises :

a surface (22) support connected to the housing (12) by at least one of its ends extending at least partially in a plane substantially perpendicular to the longitudinal plane, a longitudinal end of said workpiece (14) movable, said end (24) of contact, being adapted to be brought into contact with said surface (22) support so that a longitudinal displacement of the workpiece (14) movable causes deformation of the surface (22) 'support,

means (26, 30) for measuring the deformation of the surface (22) bearing.

2. Torque according to claim 1, characterized in that the means for measuring deformation of the surface (22) bearing comprises a sensor (26) near, connected to the housing (12) facing the surface (22 ) support, and configured to measure the displacement of the surface (22) bearing in the longitudinal direction.

3. Torque according to claim 2, characterized in that the sensor (26) is near an inductive proximity sensor.

4. Torque according to claim 1 to 3, characterized in that the end (24) and the contact surface (22) bearing are integrally connected by a fastener (28).

5. Torque according to claim 4, characterized in that the holder (28) is metallic.

6. Torque according to one of claims 1 to 5, characterized in that the surface (22) bearing is connected to the housing (12) via a support (38) formed in a material that deforms not according to the temperature variations.

7. Torque according to one of claims 1 to 6, characterized in that the means for measuring deformation of the surface (22) support comprise at least one gauge (30) of deformation disposed on the surface (22 ) support and adapted to measure a value representative of the deformation of the surface (22) bearing.

8. Torque according to one of claims 1 to 7, characterized in that the surface (22) bearing is formed of a material having the Young's modulus does not vary depending on the temperature.

9. Torque according to one of claims 1 to 8, characterized in that it comprises means for measuring the temperature.

10. A gas turbine engine comprising a transmission element, characterized in that it comprises a torque meter (10) according to one of claims 1 to 9 mechanically connected to the transmission member so as to measure the torque applied to the element transmission.