Fault protection device for rotating electrical machine bearings.

Abstract

The invention relates to a rotating machine comprising a coaxial rotor (20) and stator (30), the rotor (20) being free to rotate about an axis of rotation, the machine comprising a bearing (10) for guiding the rotation of the rotor (20), the bearing (10) being in contact with a surface (200) of the rotor (20), the bearing (10) comprising a rolling device (100) around the rotor (20) and a sensing device (110), the sensing device (110) comprising a first element (110') and a second element (110''), the first element (110') extending around the rotor (20), the second element (110'') being integral with the stator (30), the sensing device (110) being configured to switch from a resting configuration, in which the first element (110') is distant from the rotor (20) and the second element (110''), to a braking configuration,in which the first element (110') is driven in rotation by the rotor (20) and in which the second element (110'') exerts a reaction opposite to the rotation on the first element (110'), the sensing device (110) being configured to switch from the rest configuration to the braking configuration when the rotation of the rotor (20) is eccentric with respect to the axis of rotation. Figure for the abstract: Fig. 1,

Description

Title of the invention: Device for protecting against faults in rotating electrical machine bearings.

[0001] The invention relates to the field of aeronautics, and in particular to rotating electrical machines, such as motors or generators, that convert electrical energy into mechanical energy and vice versa, intended for use in means of transport, such as aircraft, for example airplanes or helicopters. However, the invention is not limited to the field of transport and is suitable for any multi-stage rotating electrical system. More specifically, the invention relates to a device for protection against a lack of concentricity in the rotation of the rotor of the rotating electrical machine.

[0002] The field of application of the invention relates to electricity generators and electrically powered motors associated with their converters, which includes: - a synchronous or asynchronous type electrical machine, but not exclusively with: • At the stator, a main winding, which can be, as a non-limiting example, polyphase; • At the rotor, a squirrel cage or magnets indifferently mounted, on the surface, or buried, and without presuming the type of magnetization or magnets; • A rotating bearing assembly or rotor rotation guide comprising, for example, a bearing to ensure the rotation of the rotor. - A shaft allowing the electrical machine to be coupled to a relay box such as a gearbox or other, via splines.

[0003] Certain events can unfortunately lead to a malfunction of the generator and / or motor assembly, including events such as: - A loss of lubrication in one of the bearings or rotation guides. This type of defect can lead to overheating of the bearing assembly and a risk of high temperature propagation up to the point of auto-ignition of the malfunctioning bearing. - Or a slow or sudden failure of one or more bearings. This type of defect can lead to a loss of rotor support relative to the stator, resulting in unwanted heat generation in the air gap and a risk of high temperature propagation.

[0004] These two events generally cause the rotor to become misaligned with respect to the stator failure and overheating of components can lead to the failure of one or even the entire machine. In such situations, it is necessary to stop the rotor's rotation to minimize damage and prevent any unwanted bursting, breakage, or fire in the rotating electrical machine.

[0005] It is known that, to avoid these dreaded events, different types of means can be used: - A mechanical fuse-type device, or "breakable section," is installed on the shaft line of the rotating machine. This type of device has the advantage of being relatively simple and compact. Its major drawback is that disengagement can only occur if the rotor torque is sufficiently high. More precisely, this breakable section functions like a fuse with a predetermined mechanical resistance. Therefore, for this fuse to break, a sufficient force, or torque, must be applied. However, a weakly resistant mechanical fuse can also break even when the shaft is sound and no unforeseen event has occurred. Such a break is only possible in the case of a mechanical blockage sufficient to slow the rotor.And in the case of a loss of lubrication in a bearing, it is possible to observe a burst or extreme heating in the rotating electrical machine without this generating a significant braking torque sufficient to break the transmission shaft. - A dynamic disengagement device consisting of an actuator that engages the two shafts, for example, the shaft of the rotating electrical machine and the shaft of the drive system. The device includes controlled disengagement means. Thus, in the event of a detected malfunction, these means are activated to disengage the shafts while they are rotating. This dynamic device can be a viable solution; however, it suffers from some major drawbacks. The volume and mass required to implement this type of device are incompatible with the space typically available for integrating the rotating electrical machine. Furthermore, disengagement can only occur on command, itself based on detection via an algorithm or upon exceeding a threshold.Consequently, the reliability of the dynamic device is strongly linked to the reliability of the detection system, the algorithm, and the control electronics. Therefore, adding such a dynamic device significantly degrades the reliability of the rotating electrical machine.

[0006] The invention aims to overcome all or part of the problems mentioned above by providing a passive and compact detection and disengagement device. The detection device makes it possible to detect any eccentricity in the rotation of the shaft and to act as soon as a defect in the rotation of the shaft is detected.

[0007] To this end, the invention relates to a rotating machine comprising a coaxial rotor and stator, the rotor being configured to be mobile in rotation about an axis of rotation x, the rotating machine comprising at least one bearing configured to guide the rotation of the rotor, the at least one bearing being in contact with a surface of the rotor, the bearing comprising a rolling device extending concentrically around the rotor and a device for detecting a rotational fault, the rotational fault detection device comprising a first element and a second element, the first element extending concentrically around the rotor, the second element being integral with the stator, the detection device being configured to switch from a resting configuration, in which the first element is distant from the rotor and the second element, to a braking configuration, in which the first element is driven in rotation by the rotor and in which the second element exerts a reaction opposite to the rotation of the rotor on the first element, the detection device being configured to switch from rest configuration to braking configuration when the rotor rotation is eccentric with respect to the x axis of rotation.

[0008] According to one aspect of the invention, the first element is juxtaposed with the rolling device along the axis of rotation x.

[0009] According to one aspect of the invention, the bearing device is distanced from the rotor surface by a first predefined distance, the first element being distanced from the rotor surface by a second distance, the second distance being defined according to the following formula: D2 = x*D}

[0010] Where D2 represents the second distance separating the rotor surface from the first element, represents the first distance separating the rotor surface from the bearing device and etx represents the predefined eccentricity detection ratio.

[0011] According to one aspect of the invention, the first element comprises a protrusion and in which the second element comprises a stop, the stop being in contact with the protrusion in the braking configuration and distant from the protrusion in the rest configuration.

[0012] According to one aspect of the invention, the protrusion is defined along an axis radial to the rotor.

[0013] The invention will be better understood and other advantages will become apparent upon reading the detailed description of a given embodiment as an example, illustrated by the attached drawing in which:

[0014] [Fig-1] [Fig. 1] represents a front view of a bearing assembly model rotating machine according to the invention;

[0015] [Fig.2] [Fig.2] represents a side view of an assembly model of a bearing rotating machine according to the invention of [Fig.1];

[0016] [Fig.3] [Fig.3] represents a schematic view of a first element of a rotation fault detection device of the [Fig.l];

[0017] [Fig.4] [Fig.4] represents a schematic view of a second element of the rotation fault detection device of the [Fig.l].

[0018] For the sake of clarity, the same elements will bear the same references in the different figures.

[0019] Figure 1 shows a front view of a bearing 10 of a rotating machine comprising a coaxial rotor 20 and stator 30. The rotor 20 is thus configured to be free to rotate about an axis of rotation X. The rotor 20 is free to rotate within the stator 30, which is fixed relative to the rotor 20. The rotating machine also includes at least one bearing 10 configured to guide the rotation of the rotor 20 in a manner aligned with the axis of rotation X. The rotor 20 of the rotating machine passes through at least one bearing 10 via a cross-section 101, as shown in [Fig. 1].

[0020] In other words, at least one bearing 10 maintains the rotation of the rotor 20 relative to the axis of rotation X- At least one bearing 10 is in contact with a surface 200 of the rotor 20.

[0021] At least one bearing 10 can be in point contact with the surface 200 of the rotor 20. Preferably, at least one bearing 10 is in permanent contact with the surface 200. In other words, at least one bearing 10 is connected to the concentric surface 200.

[0022] To this end, at least one bearing 10 comprises a bearing device 100 extending concentrically around the rotor 20. The bearing device 100 is in direct contact with the surface 200 of the rotor 20. The bearing device 100 thus allows the rotor 20 to rotate relative to at least one bearing 10. By way of example, the bearing device 100 can be any type of bearing that ensures the rotational movement of the rotor 20 relative to at least one fixed bearing 10. Preferably, the bearing device 100 is a ball bearing.

[0023] The at least one bearing 10 also includes a detection device 110 for detecting a rotor 20 rotation fault. The detection device 110 is configured to switch from a resting configuration to a braking configuration of the rotor 20 if the at least one bearing is no longer guided and produces orbital motion, i.e., its rotation is no longer perfectly concentric, and frictional contact with surrounding elements occurs. ronnants. The detection device 110 acts as a freewheel type mechanism which is not directly driven in rotation and mounted with a clearance relative to rotor 20.

[0024] The rotation fault detection device 110 comprises a first torque amplifier element 110' and a second element 110'' that detects a rotational eccentricity of the rotor 20. The first element 110' or torque amplifier of the rotor 20 is an element extending concentrically around the rotor 20, in a manner similar to the bearing device 100.

[0025] In the resting configuration of the rotation fault detector 110, the first element or torque amplifier of the rotor 110' is a free element, i.e., free to rotate, in the same way as the rotor 20, but not necessarily driven in rotation by the rotor 20. In other words, the first element 110' or torque enhancer of the rotor 20 is free to rotate relative to the rotor 20 and relative to the stator 30 and there is a clearance or distance between the rotor 20 and the first element 110'.

[0026] The second element 110' ' or detector of an eccentricity of the rotation of the rotor 20 is an element fixed to the stator 30 and fixed with respect to the rotor 20.

[0027] Furthermore, in the resting configuration of the rotor 20 rotation fault detector 110, the first element 110' or rotor 20 torque enhancer is separated from the rotor 20 and the second element 110”. Thus, the rotor is connected to at least one bearing 10 only via the bearing device 100, and the second element 110' is not connected to the first element 110', the rotor 20 torque enhancer. In other words, the first element 110', or rotor 20 torque enhancer, is disconnected from the rotor 20 and the second element 110”.

[0028] This resting configuration of the rotation fault detector 110 thus reflects a nominal operation of the rotating machine and the rotor 20. More precisely, the resting configuration allows us to conclude that the rotation of the rotor 20 is substantially concentric and that the axis of rotation x of the rotor 20 is not mobile during the rotation of the rotor 20.

[0029] In the braking configuration of the detection device 110, the first element 110' or torque enhancer of the rotor 20 is driven in rotation by the rotor 20. Any type of drive can be considered, such as a magnetic drive using magnets between the rotor 20 and the first element 110'. Preferably, the first element 110', when driven in rotation by the rotor 20, is then mechanically connected to the rotor 20.

[0030] More precisely, when the rotation of the rotor 20 is no longer concentric, that is, when the axis of rotation x of the rotor 20 is mobile in any way, then this eccentricity is detectable at the level of the first element 110'. Indeed, the rotation The imperfect shape of rotor 20 and the eccentricity of its rotation allow it to come into contact with the first torque-increasing element 110'. This first torque-increasing element 110' is then driven by rotor 20, due to the mechanical contact between the rotating rotor and the rotating element 110', in a manner similar to that of rotor 20.

[0031] Thus, unlike the resting configuration, in the braking configuration of the detection device 110, the rotor 20 and the first element 110' perform rotations.

[0032] The first element 110', once driven by the rotor 20, thus increases the rotational torque of the rotor 20. Indeed, the torque of the rotor 20 is a combination of the torque of the rotor 20 and the first element 110'. Furthermore, it can be envisaged that the first element 110 has a larger dimension than the rotor 20. More precisely, if the first element 110' is circular, as shown in [Fig. 1], it can be envisaged that the cross-section, or diameter of the first element 110' is greater than the diameter or cross-section of the rotor 20, so that the rotation of the first element 110' significantly increases the rotational torque of the rotor 20, when the rotor 20 drives the first element 110' in rotation.

[0033] Alternatively, it may also be envisaged that the first element be denser or have a higher density than the density or mass density of the rotor 20 in order to increase the rotational torque of the rotor 20, when the rotor 20 drives the first element 110' in rotation.

[0034] In the braking configuration, the second element 110” also exerts a reaction opposite to the rotation of the rotor 20 on the first element 110'. Thus, the second element 110” acts as a brake with respect to the first element 110' and with respect to the rotor 20. By way of illustrative example, the second braking element 110' can act as a magnetic brake with respect to the first torque-increasing element 110' and with respect to the rotor 20. Indeed, the first element 110' and the second element 110” can comprise magnets with opposite poles so that when the first element 110' is driven in rotation by the rotor 20, the magnets of the first element 110' are brought closer to the magnets of the second element 110”. The magnets of the second element 110” then apply a magnetic repulsion force opposite to the torque of the rotor 20 and the first element 110’ torque enhancer of the rotor 20.

[0035] Preferably, in the braking configuration, the second element 110” or brake is in mechanical contact with the first element 110', which increases the torque of the rotor 20. Thus, the second element 110” acts as a mechanical stop against the rotation of the first element 110' and the rotor 20. The second element 110'' therefore blocks any rotation of the first element 110' and the rotor 20 about the axis of rotation x.

[0036] Preferably, the second element 110” is of complementary shape to the first element 110'.

[0037] Thus, when the rotation of the rotor 20 is no longer concentric, that is, when the axis of rotation x of the rotor 20 is mobile in any way, then the rotor 20, by virtue of its inhomogeneous motion and its eccentricity, causes the first element 110' to rotate, which thereby acts as a means of increasing the torque of the rotor 20 by rotating with the rotor 20. Consequently, this increased torque is detected by the detection device 110 by means of the second element 110', which comes into contact with the first element in order to stop all rotation of the rotor 20 and the first element 110'. The rotor 20 is thus immobilized before its rotation degenerates too rapidly.

[0038] In other words, the detection device 110 is configured to switch from the resting configuration to the braking configuration when the rotor rotation is eccentric with respect to the axis of rotation x. Eccentric means that the behavior and rotation of the rotor 20 deviates from the nominal or expected rotation of the rotor 20, or that the rotation of the rotor 20 no longer defines a concentric circle but rather an elliptical or ovoid motion. Furthermore, the rotation of the rotor 20 defines a radius R, which is the distance between the axis of rotation X and the surface 200 of the rotor 20 along a plane perpendicular to the axis of rotation x, as shown in Figure 1. Therefore, an eccentricity is also a distance between the axis of rotation x and the surface 200 of the rotor 20 along a plane perpendicular to the axis of rotation x when the rotational motion of the rotor 20 is no longer concentric.Thus, the eccentricity, when the rotational movement of the rotor 20 is no longer concentric, is greater than the radius R.

[0039] The bearing device 100 also includes a tolerance with respect to the rotation of the rotor 20. The tolerance of the bearing device 100 is a radial distance to the rotor 20, i.e., along a radial axis R, defined within which the rolling function of the bearing device 100 is performed. If the rotational movement of the rotor 20, in other words, if there is an eccentricity in the rotor's rotation, exceeds this operating tolerance, then the bearing device 100 performs its function of rolling the rotor 20 in a degraded manner. This tolerance can thus be interpreted as a clearance between the rotor 20 and the bearing device 100.

[0040] The first element 110' is also positioned in the immediate vicinity of the rotor 20. The first element 110' then also includes a second tolerance with respect to the rotation of the rotor 20. And, as with the bearing device 100, this second tolerance is a radial distance to the rotor 20, that is, along the radial axis. However, unlike the bearing device 100, the second tolerance translates into the threshold distance indicating whether the rotor is functioning properly or not. 20. In other words, if the rotational movement of the rotor 20, or if the potential eccentricities in the rotation of the rotor 20, remain less than the distance defined by the second tolerance, then the rotor 20 operates nominally. Consequently, the first element 110' is not driven by the rotor, and the detection device 110 is in its resting configuration. Conversely, if the potential eccentricities in the rotation of the rotor 20 exceed the distance defined by the second tolerance, then the rotor 20 operates in a degraded state. The first element 110' is then driven in rotation by the rotor 20, which preferentially comes into contact with the first element 110', and the detection device 110 then switches to its braking configuration. Consequently, the first tolerance of the bearing device 100 is less than the second tolerance of the detection device 110.In this way, in the resting configuration of the sensing device 110, the rotor 20 is in contact only with the bearing device 100. And, in the braking configuration, the eccentricity measurable at the level of the rotation of the rotor 20 allows the rotor 20 to drive the first element 110' in rotation and to detect this eccentricity by means of the second element 110”.

[0041] By way of illustrative example, for a bearing device 100 having a tolerance of 7 micrometers, i.e., a distance of 7 micrometers between the surface 200 of the rotor 20 and the bearing device 100, the second tolerance, or distance between the surface 200 of the rotor 20 and the first element 110', can be considered to be 10 micrometers. Advantageously, the distance between the surface 200 of the rotor 20 and the first element 110', namely the second tolerance, can be defined relative to the distance between the surface 200 of the rotor 20 and the bearing device 100. More precisely, the distance between the surface 200 of the rotor 20 and the first element 110', namely the second tolerance, can be defined according to the following formula: D2 = x*Dl

[0042] Where D2 represents the distance separating the surface 200 of the rotor 20 from the first element 110, namely the second tolerance, D\ represents the distance separating the surface 200 of the rotor 20 from the bearing device 100, namely the first tolerance, etx represents the eccentricity detection ratio.

[0043] Preferably, the eccentricity detection ratio x is greater than 1 and less than 1.5. In an ideal configuration, the eccentricity detection ratio x is equal to 1.2.

[0044] Preferably, the first element 110' is juxtaposed with the bearing device 100 with respect to the axis of rotation x. Therefore, from the point of view of the plane perpendicular to the axis of rotation x, the first element 110' and the bearing device 100 are superimposed. The first element 110' and the bearing device 100 are therefore positioned side by side, and preferably close to each other along the axis of rotation X-H it is not necessary that the first element 110' and the bearing device 100 be linked.

[0045] Ideally, the first element 110' is fixed against the bearing device 100 so as to allow the detection device 110 to detect any eccentricity as close as possible to the bearing device 100.

[0046] The first torque-increasing element 110' also includes at least one projection 410. This at least one projection 410 is in the form of a protrusion. The second brake element 110" includes a mechanical stop 420 with a shape complementary to the projection 410, enabling the at least one projection 410 to bear against or support the stop 420. Preferably, the first brake element 110' includes at least two projections 410 and the second brake element 110' includes the same number of mechanical stops 420.

[0047] Thus, in the braking configuration, at least one protrusion 410, which undergoes rotation from the first element 110', comes into contact with the mechanical stop 420, which exerts a force opposing the rotational torque. Conversely, in the rest configuration of the detection device 110, at least one protrusion 410 is distant from the stop 420.

[0048] In addition, at least one outgrowth 420 can extend preferentially along the radial axis R.

[0049] Alternatively, at least one protrusion 410 can extend parallel to the axis of rotation X- This architecture then allows the first element 110' and the second element 110' ' to be offset along the axis of rotation x so as to guarantee a distance between the first element 110' and the second element 110' ' in the rest configuration of the detection device 110.

[0050] Figure 2 shows a cross-sectional view of the bearing of Figure 1 along a plane parallel to the axis of rotation X-

[0051] Furthermore, it may also be considered to add, in addition to the detection device 110, a mechanical fuse at the rotor. The mechanical fuse then allows for a mechanical disengagement in the rotor 20 when the detection device 110 switches to the braking configuration. Indeed, as stated previously, the braking configuration allows for the generation, via the second element 110”, of a braking force opposing the rotational torque of the rotor 20 that is significant and sufficient for the mechanical fuse to activate and break. Thus, when the rotation of the rotor 20 is no longer concentric, that is, when the axis of rotation x of the rotor 20 is mobile in any way, then the rotor 20, due to its inhomogeneous motion and eccentricity, causes the first element 110' to rotate, which thus acts as a means of increasing the torque of the rotor 20 by rotating with the rotor 20. Consequently, this increased torque is detected by the detection device 110 by means of the second element 110” which comes into contact with the first element 110' so as to generate a friction torque sufficient to break the section to be broken, i.e. the mechanical fuse, in order to stop all rotation of the rotor 20 and the first element 110'. The rotor 20 is then immobilized before its rotation degenerates too strongly.

[0052] Figure 3 shows a schematic view of a preferred architecture of the first element 110' for increasing the torque of the rotor 20 during its rotation, when the rotation of the rotor 20 is eccentric. Preferably, the first element 110' partially takes the form of an annular ring and, as such, includes at least one concentric section 405 adapted to the shape of the rotor 20. As stated previously, the first element 110' also includes, as previously stated, at least one projection 410.

[0053] As stated previously, the rotor 20 is distant from at least one concentric section 405. By way of indicative example, the clearance, i.e. the distance separating the surface 200 of the rotor 20 from the concentric section 405 of the first element 110' can be between 0.001% and 0.05% of the diameter of the rotor 20. By way of indicative example, the clearance between the surface 200 of the rotor 20 and the concentric section 405 of the first element 110' can be between 0.02 millimeters and 5 millimeters.

[0054] Thus, when the rotation of the rotor 20 is no longer perfectly concentric and the surface 200 is in contact with the concentric section 405, the first element 110' is driven in rotation with the rotor 20 until the protrusion 410 is in contact with the stop 420 and immobilizes the assembly rotor 20 and first element 110'.

[0055] By way of example, in order to rotate the first element 110' by means of the contact between the surface 200 and the concentric section 405, the friction torque between the surface 200 and the concentric section 405 must be greater than 0.5 Nm

[0056] Advantageously, the first element 110' can also include a damping section 415 disposed near the protrusion 405. More precisely, along a plane perpendicular to the axis of rotation x of the rotor 20, the stop 420 of the second element 110" is located between the damping section 415 and the protrusion 410 of the first element 110'. Indeed, since the local stresses at the interface between the protrusion 410 and the stop 420 are high, and by way of example, greater than 800 MPa, the damping section 415 withstands these stresses by deforming, in particular to prevent any breakage of the first element 110'. The damping section 415 acts like a compression spring to withstand the local stresses during braking of the first element 110' and the rotor 20.

[0057] The second element 110'' shown in [Fig.4], comprises at least one stop 420 configured to interact directly with at least one protrusion 410 of the first element 110' when the first element 110' is driven in rotation by the rotor 20.

[0058] The invention thus proposes a so-called passive disengagement device. Indeed, during a loss of lubrication or a slow or sudden failure of a bearing, this failure leads to a loss of guidance of the bearing, whether of the roller or other type. The detection device 110 then makes it possible to detect the orbit of the rotor 20 and produce a torque resisting the rotation of the rotor 20. The invention also makes it possible to avoid adding any additional controlled elements other than those provided for the operation of the rotating machine, and therefore advantageously has no impact on the volume and a negligible impact on weight.

Claims

Claims

1. A rotating machine comprising a coaxial rotor (20) and stator (30), the rotor (20) being configured to be rotatable about an axis of rotation x, the rotating machine comprising at least one bearing (10) configured to guide the rotation of the rotor (20), the at least one bearing (10) being in contact with a surface (200) of the rotor (20), the bearing (10) comprising a rolling device (100) extending concentrically around the rotor (20) and a device (110) for detecting a rotation defect, the rotation defect detection device (110) comprising a first element (110') and a second element (110”), the first element (110') extending concentrically around the rotor (20), the second element (110”) being integral with the stator (30), the detection device (110) being configured to switch from a configuration rest, in which the first element (110') is distant from the rotor (20) and from the second element (110”),to a braking configuration, in which the first element (110') is rotated by the rotor (20) and in which the second element (110”) exerts a reaction opposite to the rotation of the rotor (20) on the first element (110'), the detection device (110) being configured to switch from the rest configuration to the braking configuration when the rotation of the rotor (20) is eccentric relative to the axis of rotation x.,

2. Rotating machine according to claim 1, in which the first element (110') is juxtaposed with the rolling device (100) along the axis of rotation X-

3. A rotating machine according to claim 1, wherein the rolling device (100) is spaced from the surface (200) of the rotor (20) by a first predefined distance, the first element (110') being spaced from the surface (200) of the rotor (20) by a second distance, the second distance being defined according to the following formula: D2 = x*D} Where D2 represents the second distance separating the surface (200) of the rotor (20) from the first element (110), represents the first distance separating the surface (200) of the rotor (20) from the rolling device (100) and x represents the predefined eccentricity detection ratio.

4. A rotating machine according to claim 1, wherein the first

5. element (110') comprises a protrusion (410) and wherein the second element (110”) comprises a stop (420), the stop (420) being in contact with the protrusion (410) in the braking configuration and distant from the protrusion (410) in the rest configuration. Rotating machine according to claim 4, in which the protrusion (410) is defined along an axis radial to the rotor (20).

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