FR3130468A1 - Device for disconnecting a generator driven by a rotor, associated generator-motor assembly. - Google Patents

Abstract

This disconnection device (2) of a generator (1) comprises an internal shaft (6) mounted axially movable between an engagement position in which the internal shaft (6) is coupled to a drive rotor (5) and a disengagement position in which the internal shaft (6) is disengaged from the drive rotor (5), the disconnection device (2) comprising means for braking and locking in rotation (12) of a nut ( 10) mounted axially immobile on the internal shaft (6), the axial displacement of the internal shaft (6) being caused by the means for braking and locking in rotation (12) of the nut, the braking means and for locking the nut in rotation (12) comprising an electromagnet (18), the disconnection device (2) comprising automatic locking means (13) and unlocking means (14) controlled remotely from the disengaged position of the internal shaft (6). Figure for abstract: Fig 1

Description

Device for disconnecting a generator driven by a rotor, associated generator-motor assembly.

The invention relates, in general, to engines equipped with rotating machines.

More particularly, the invention relates to a system for disconnecting a generator driven by an engine in the event of a malfunction in the generator.

Prior techniques

More and more frequently, rotating machinery such as generators or electric motors are mounted on engines such as aircraft engines. These rotating machines are mounted so that the gearbox or the motor shaft drives the rotating machines in rotation. Aircraft engines are thus supplied with electricity by generators which are driven by the engine. More precisely, the generators are driven via the transmission box, also called gearbox, or directly by the motor shaft.

In the event of a malfunction of one of the elements of the generator, it is necessary to disconnect the generator from the engine in order to protect the engine. Indeed, an additional resistive load can be produced, for example by the short-circuiting torque or by a blocking of the generator, which can cause a risk of fire and/or damage the generator as well as the engine nacelle.

Existing disconnection devices comprise a shear section at the level of the drive shaft of the generator capable of breaking from a certain torque threshold transmitted to the generator.

Also, until recently, most generators were wound rotor generators, which allowed a short circuit to be suppressed by cutting off the field current to the rotor.

However, current generators are variable frequency and operate over wider ranges of rotational speeds. Also, generators are increasingly permanent magnet generators, and shorting them produces a torque that cannot be suppressed, similar to wound-rotor generators. Moreover, the torque of this short-circuiting depends on the speed and the type of short-circuiting.

It is therefore essential to adapt the disconnection systems to current generators.

Some disconnect systems have adapted the shear section technique. However, such disconnection devices are not reusable and must be changed following a malfunction resulting in the activation of the device.

Other solutions have therefore been developed, including controlled and reusable disconnect devices for spline couplings between the motor output shaft and the generator input shaft. These disconnection systems are based in particular on a principle of axial displacement of one of the axes relative to the other so as to disengage the splines, for example from the input shaft of the generator.

In these systems, in normal operation, the motor drives the generator input shaft until a malfunction occurs. The axial displacement of this input shaft is caused by the blocking or braking in rotation of a nut linked to this shaft. Braking devices therefore have the function of braking this nut. Some of these disconnection devices comprise a locking mechanism intended to lock the input shaft in the disconnected position, this device being activatable by the input shaft when it moves axially up to means for activating the lockdown.

Once the lock is active, the input shaft cannot return to the engaged position, but is free to rotate and can continue to move under the action of its kinetic energy. For this, means of slowing down and blocking the rotation of the internal shaft, which can be activated after locking, have been developed. It may for example be a shoulder abutting against a side face of the nut. These means are therefore effective as long as the nut is locked in rotation by the braking device. The braking device therefore has the function on the one hand of blocking the nut to move the input shaft during disconnection, and on the other hand of blocking the nut after locking in order to allow the blocking of the input shaft driven by its kinetic energy.

During disconnection, the braking device must therefore develop a torque equivalent to the friction forces at the connection with the input shaft of the nut and at the splines.

After locking, the device must therefore develop a torque equivalent to the kinetic energy of the input shaft.

The object of the present invention is therefore to overcome the aforementioned drawbacks and to propose a device for disconnecting a generator driven by a motor equipped with a braking device that meets the aforementioned requirements.

The present invention therefore relates to a device for disconnecting a generator, comprising an internal shaft mounted axially movable between an engagement position in which the internal shaft is coupled to a drive rotor and a disengagement position in which the internal shaft is disengaged from the drive rotor, the disconnection device comprising means for braking and locking in rotation a nut mounted axially immobile on the internal shaft, the axial displacement of the internal shaft being caused by the means for braking and locking the nut in rotation, the means for braking and locking the nut in rotation comprising an electromagnet, the disconnection device comprising automatic locking means and unlocking means controlled remotely from the disengaged position of the internal shaft.

In one embodiment, the electromagnet is mounted on the internal shaft and comprises two opposite polarities and arranged facing each other so as to be radially separated by a recess intended to receive a shoulder of the nut .

Advantageously, the means for braking and locking the nut in rotation comprises an axially movable part between a rotationally locking position of the nut and an unlocking position, the locking position being reached under the effect of the activation of the electromagnet.

In one embodiment, the axially movable part is coupled to the nut, the braking and locking means comprising an abutment element able to block rotation of the movable part when the movable part is in the position of locking in rotation of the nut.

Advantageously, the nut is coupled to the internal shaft by screwing with balls or rollers.

In other embodiments, the means for braking and locking in rotation comprises at least one ball and a cavity for adjusting the force exerted on the ball, the ball being able to be placed in the cavity, the position of blocking corresponding to an increased force exerted on the ball and the unlocking position corresponding to a reduced force exerted on the ball.

In one embodiment, the movable part comprises a surface in contact with the ball, the surface comprising the cavity, the ball being disposed between the surface of the movable part and the nut so that the ball is housed in the cavity when the moving part is in the unlocking position, and that the ball is compressed by the surface of the moving part when the moving part is in the locking position.

In a final embodiment, the means for braking and locking the nut in rotation comprises friction linings, the ball being placed in the cavity, the cavity being of variable depth, the axially movable part being capable of activating a means for moving the ball in the cavity under the effect of the activation of the electromagnet, the blocking position corresponding to a thrust exerted by the ball on the friction linings against the nut exerted by the ball and the position release corresponding to an absence of thrust exerted by the ball on the friction linings.

The present invention also relates to an assembly comprising a motor and a generator, the motor driving the generator by its shaft in rotation, the generator being equipped with a disconnection device as described above.

Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

illustrates a view in longitudinal section of a generator equipped with a disconnection device according to the invention in the engagement position on a drive rotor; And

illustrates a view in longitudinal section of a generator equipped with a disconnection device according to the invention in the locked disengagement position with respect to the drive rotor;

illustrates a view in longitudinal section of a first embodiment of a means for braking the rotation of the nut;

illustrates a cross-sectional view of the first embodiment of Figure 3 along the line III-b-III-b;

illustrates a view in longitudinal section of a second embodiment of a means for braking the rotation of the nut; And

illustrates a view in longitudinal section of a third embodiment of a means for braking the rotation of the nut;

Detailed description of at least one embodiment

We represented on the a view in longitudinal section of a generator 1 equipped with a disconnection device 2 according to the invention.

The generator 1 comprises a rotor 3 and a stator 4. It can be a wound rotor or permanent magnet generator.

In operation, the generator 1, and more particularly the rotor 3 of the generator 1 is driven in rotation by a drive rotor of the generator 5. The drive rotor 5 is more precisely an output shaft of an engine. This engine is for example an engine of a vehicle such as an aircraft.

Nevertheless, the invention is not limited to this configuration, and also relates to a device for disconnecting a generator driven by a gearbox, or transmission box.

The disconnection device 2 comprises an internal shaft 6, an external shaft 7, means 8 for coupling the internal shaft 6 to the external shaft 7, a monitoring device and means 9 for disengaging the coupling means .

The internal shaft 6 extends axially in the generator and is secured to the rotor 3 of the generator 1. More specifically, the rotor 3 is fixed axially on the internal shaft 6. On the other hand, the internal shaft 6 is capable to be secured to the outer shaft 7 and to disengage. The outer shaft 7 is attached to the drive rotor 5, and extends axially between the drive rotor 5 and the inner shaft 6.

The inner shaft 6 is mounted axially movable between an engagement position in which it is coupled to the outer shaft 7 illustrated in the and a disengagement position of the outer shaft 7.

On the , the generator 1 is in the operating position and is therefore driven by the drive rotor 5 via the inner shaft 6 in the position of engagement on the outer shaft 7, which is fixed to the drive rotor 5.

At one of its ends 6a opposite the outer shaft 7, the inner shaft 6 comprises coupling means 8. These coupling means 8 are able to secure the inner shaft 6 to the outer shaft 7. More particularly, these coupling means 8 comprise teeth or curved splines engaged axially with the external shaft 7. Thus, their disengagement is possible by a simple translation of the internal shaft 6 so as to move it axially away of the outer shaft 7 over a distance greater than the length in engagement of the coupling means 8 on the outer shaft 7.

In the position of the device 2 illustrated on the , the drive rotor 5 is capable of rotating the internal shaft 6 secured to the rotor 3, via the external shaft 7. The generator 1 is therefore in the normal operating position.

The disconnection device 2 comprises a monitoring device not shown in the figures. This monitoring device comprises sensors capable of detecting a malfunction in the generator 1 such as a short circuit or a blockage of the generator. The monitoring device is also capable of triggering the disengagement means 9 of the coupling means 8, when a malfunction occurs.

The disengagement means 9 of the coupling means are able to deactivate the coupling means 8. More particularly, the disengagement means 9, when they are activated, cause an axial translation of the internal shaft 6 so that the coupling means 8 disengage from the external shaft 7 fixed to the drive rotor 5, which disconnects the generator 1 from the drive rotor 5 and therefore from the motor.

The disengagement means 9 comprise a nut 10, translation locking means 11 and a braking and locking means 12 in rotation of the nut 10.

The nut 10 is mounted on the internal shaft 6, for example on the end 6c of the internal shaft 6 opposite the end 6a comprising the coupling means 8.

In a first embodiment, the nut 10 comprises an internal thread by which it is secured to an external thread 6b of the internal shaft 6

The translation locking means 11 of the nut 10 are secured to the stator 4 of the generator 1. The translation locking means 11 are in contact with the nut 10 and block its axial translation, without blocking its rotation. For example, the translation locking means 11 of the nut 10 comprise angular contact bearings fixed on the one hand to the stator 4 and on the other hand arranged on the nut 10 so as to block its axial translation without blocking its rotation driven by the rotation of the internal shaft 6.

The braking and locking means 12 in rotation of the nut 10 is capable of braking the rotation of the nut 10 driven by the rotation of the internal shaft 6, preferably until the rotation of the nut 10. The braking and locking means 12 is for example an electromechanical braking device capable of delivering a braking torque opposite to the torque transmitted by the drive rotor 5 via the external shaft 7 and the internal shaft 6 to nut 10 and to the short-circuiting torque in the event of a malfunction.

The translation blocking means 11 are permanently activated while the braking and blocking means 12 are only activated in the event of a malfunction. Thus, when the generator 1 operates and is driven in rotation by the drive rotor 5 via the external shaft 7 and the internal shaft 6, the nut 10 also undergoes a rotational movement driven by the internal shaft 6 , but does not translate axially.

On the other hand, in the event of a malfunction, the nut 10 is immobilized in rotation and in translation, the braking and locking means 12 then also being activated.

When it detects a malfunction, the monitoring device activates the disengagement means 9 of the coupling means. The disengagement means 9 then block the rotation and the translation of the nut 10, which is then immobilized. The immobilized nut 10 then exerts a resistance force on the rotating shaft 6 which causes an axial translation of the internal shaft 6 so that the shaft 6 moves axially away from the external shaft 7 fixed on the rotor. drive 5. The axial translation of the inner shaft 6 causes the disengagement of the coupling means 8 from the outer shaft 7 once the axial translation length of the inner shaft 6 is greater than the length in engagement coupling means 8 on the outer shaft 7.

The disconnection device 2 also comprises means 13 for locking and means 14 for unlocking the internal shaft 6 in the disengaged position, intended to prevent unwanted re-engagement of the internal shaft 6, after its disengagement from the shaft. external 7.

The locking means 13 are automatic and the unlocking means 14 are remote controlled.

The locking means 13 make it possible to maintain the generator 1 in the disconnected position and to avoid any re-engagement. These locking means 13 can only be engaged after disengagement over a stroke corresponding to the overall relative displacement between the external shaft 7 fixed to the drive rotor 5 and the internal shaft 6, in order to ensure complete disengagement. in all cases of operation.

The locking means 13 comprise an abutment element 13a and a first shoulder 13b of the internal shaft 6.

This stop element 13a is able to move radially between an axial locking position of the shoulder 13b of the internal shaft 6 represented on the and an axial release position of the shoulder 13b. More particularly, the stop element 13a is arranged in the generator 1 so as to be on the path of the shoulder 13b of the internal shaft 6 in axial translation during its disengagement movement. The stop element 13a is then in the position of axial blocking of the shoulder 13b. The stop element 13a is also arranged in the generator 1 so as not to be on the path of the shoulder 13b of the internal shaft 6 in axial translation when it is reengaged. The stop element 13a is then in the axial unlocking position.

The stop element 13a comprises a face 13c positioned opposite the shoulder 13b of the internal shaft 6 in the engaged position on the external shaft 7.

The stop element 13a further comprises a face 13d positioned opposite the shoulder 13b of the internal shaft 6 in the disengaged position of the external shaft 7 locked. The face 13d extends substantially radially relative to the axis of translation of the internal shaft 6.

The shoulder 13b comprises a face 13e and a face 13f. Face 13e extends substantially radially as far as a free radial end which is connected to face 13f.

The face 13f of the shoulder 13b is positioned opposite the face 13c of the abutment element 13a when the internal shaft 6 is in the engaged position on the external shaft 7. Thus, the face 13f is able to come into contact with the face 13c of the abutment element 13a when the internal shaft 6 is in disengagement translation of the external shaft 7 and in disengagement locking movement.

Face 13e is positioned opposite face 13d of the abutment element when internal shaft 6 is in the disengaged position from external shaft 7 and locked. Thus, face 13e is able to come into contact with face 13d of abutment element 13a when internal shaft 6 is disengaged from external shaft 7 in the locked position.

The face 13c is configured to allow the locking of the internal shaft 6 in axial translation. More precisely, the face 13c extends between two radial ends and is oblique with respect to the axis of translation of the internal shaft 6 so that the end of the face 13c closest to the axis of translation of the internal shaft 6 is axially closer to the plane perpendicular to the axis of translation of the internal shaft 6 and comprising the face 13d than the second radial end of the face 13c.

Possibly, the face 13f is also oblique with respect to the axis of translation of the internal shaft 6, so as to be parallel to the face 13c.

In this way, the stop element 13a does not block the axial translation of disengagement of the internal shaft 6, and blocks the axial translation of reengagement of the internal shaft 6 in the disengaged and locked position. Indeed, when the internal shaft 6 is in axial translation disengaging from the external shaft 7, the face 13f of the shoulder 13b comes into contact with the oblique face 13c of the abutment element 13a, and applies a force which will move radially away the abutment element 13a and allow the complete passage of the shoulder 13b.

The abutment element 13a is connected to a biasing means 15 such as a compression spring tending to return the abutment element 13a to the axial locking position of the shoulder 13b.

In other words, under the effect of the contact of the faces 13c and 13f due to the axial movement of disengagement of the internal shaft 6 which is against the biasing means 15, the abutment element 13a moves radially to release the axial translational movement of the shoulder 13b up to the locking position, and resumes an axial locking position of the shoulder 13b once the locking position has been reached by the internal shaft 6.

Indeed, once the shoulder 13b has crossed the abutment element 13a axially, the abutment element 13a is returned to the axial locking position by the biasing means 15. This situation is illustrated on the , which illustrates the inner shaft 6 in the disengaged and locked position of the outer shaft 7 attached to the drive rotor 5.

The shoulder 13b on the has crossed the stop element 13a and the internal shaft 6 is locked in the disengaged position. In the event of translational movement in the opposite direction of the internal shaft 6 so that the internal shaft 6 approaches the external shaft 7 fixed to the drive rotor 5, the shoulder 13b is blocked by the abutment 13a in the axial locking position, and more particularly by the face 13d of the abutment element 13a perpendicular to the shoulder 13b.

The locking of the internal shaft 6 in the position of disengagement from the external shaft 7 fixed to the drive rotor 5 is therefore obtained only after a minimum axial stroke of the internal shaft 6 under the effect of the residual kinetic energy generated by the rotation of the external shaft 7 fixed to the drive rotor 5. Indeed, when the disengagement means 9 are activated, the internal shaft 6 driven in rotation by the external shaft 7 fixed to the rotor drive 5 moves axially then disconnects from the outer shaft 7 under the effect of the locking in rotation of the nut 10. Once disconnected from the outer shaft 7, the assembly comprising the inner shaft 6 and rotor 3 continues to be driven in rotation by the rest of the kinetic energy which had been transmitted to it by the drive of rotor 5.

Thus, the locking means 13 are automatic in that they are mechanically activated independently of the will or action of a user such as a pilot, and caused solely by the movement of the internal shaft 6.

The drive rotor 5 is for example an output shaft of a motor, and can therefore have a length of several meters. In addition, the drive rotor 5 evolves in a hot environment due in particular to its rotational movement. The drive rotor 5 is therefore subject to significant axial expansion, which can cause malfunctions in the locking system of the internal shaft 6 during the disengagement of the external shaft 7, in particular by modifying the minimum travel distance of the internal shaft 6 to activate the locking means 13.

The drive rotor 5 is assembled with the outer shaft 7 by a connection 16 in which the drive rotor 5 is able to expand axially without modifying the axial position of the outer shaft 7. For example, the rotor of drive 5 is secured to the outer shaft by a shoulder of the drive rotor 5 inserted into a slot of the outer shaft 7, the shoulder and the slot not being shown in the figures.

In this way, an axial expansion of the drive rotor 5 causes localized sliding along the connection to the external shaft 7, without the axial position of the external shaft 7 being modified. The outer shaft 7 is therefore mounted axially immobile with respect to the axially expanded drive rotor 5. The outer shaft 7 being axially stationary, the relative distance between the outer shaft 7 and the inner shaft 6 is constant despite the expansion of the drive rotor 5. In addition, the outer shaft 7 being much shorter than the drive rotor 5, its expansion is negligible compared to the length in engagement. Also, the outer shaft 7 includes a ball bearing 7a. The spherical bearing 7a comprises an external cage fixed to a frame 7b fixed with respect to the drive rotor 5 and to the stator 4, so that the spherical bearing 7a axially holds the external shaft 7 and corrects the radial misalignments and the angular deviations of the outer shaft 7. In this way, the minimum travel distance of the inner shaft 6 when disengaging the outer shaft 7 to activate the locking means 13 is constant and the length in engagement of the means of coupling 8 is constant. Thus, the minimum kinetic energy for disengagement is constant and allows locking. As long as the splines are engaged, the rotation of the drive rotor 5 and the locking of the nut 10 ensure the axial displacement of the internal shaft 6 up to the activation position of the locking means 13. The risk re-engagement of the teeth is therefore eliminated.

The disconnection device 2 comprises means 17 for slowing down and locking in rotation of the internal shaft 6 which can be activated after the locking of the disengagement position of the external shaft 7. In this way, in the event of too much residual kinetic energy important, the means for slowing down and locking in rotation 17 of the internal shaft 6 are activated and the internal shaft 6 is immobilized to avoid continuing to drive the rotor 3 and risking damage to the motor or the generator.

The means 17 for slowing down and locking in rotation 17 of the internal shaft 6 comprise a second shoulder 17a of the internal shaft 6 and a stop 17b. This shoulder 17a is arranged in contact with the thread 6b which is arranged at the end 6c of the internal shaft 6. The shoulder 17a thus positioned is intended to come into contact with the stop 17b during the axial displacement of the internal shaft 6, and more specifically when the internal shaft 6 exceeds a certain axial travel distance. The shoulder 17a is thus blocked and the internal shaft 6 is immobilized as long as the stop 17b is immobile.

For example, the stop 17b is constituted by the nut 10 immobilized in rotation and in translation, and more precisely by the side face of the nut 10. Thus, in the case where the kinetic energy of the internal shaft 6 in disengagement movement is significant, the internal shaft 6 activates the locking means 13 and continues its course until it comes into contact against the side surface of the nut 10. The nut 10 being immobilized by the translation locking means 11 and by the means of braking and locking in rotation 12, the internal shaft 6 cannot continue its course and is also immobilized in rotation and in translation.

The stop 17b is positioned axially so that the contact with the shoulder 17a takes place after the locking means 13 have been activated. In this way, too much kinetic energy of the internal shaft 6 during the disengagement stroke is managed so that the risks of damage are eliminated.

The unlocking means 14 comprise a means 14a for lifting the abutment element 13a and a means 14b for returning the internal shaft 6 to the engagement position on the external shaft 7 fixed to the drive rotor 5.

The unlocking means 14 can be activated at zero speed of the drive rotor 5.

The lifting means 14a is an electromagnet, the activation of which radially moves the abutment element 13a away from the internal shaft 6, the attraction exerted by the electromagnet being greater than the restoring force of the spring 15. In this way , the stop element 13a is moved from its axial locking position to its axial unlocking position by the activation of the lifting means 14a. The return means 14b in the engagement position of the inner shaft 6 can then cause the axial displacement of the inner shaft 6 from the disengagement position to the engagement position on the outer shaft 7 fixed to the rotor drive 5. The return means 14b is for example a return spring in the engagement position positioned axially in abutment against the internal shaft 6.

Thus, the unlocking means 14 make it possible, when activated, to return the generator 1 to the operating configuration of the .

The unlocking means 14 are therefore controlled remotely, since they are controlled by a user such as the pilot who issues an activation command, for example by pressing a button, causing the activation of the lifting element 14a . In other words, the unlocking means 14 do not require manual intervention by a user directly on the device 2.

FIGS. 3, 4 and 5 respectively illustrate a first, a second and a third embodiment of a braking means 12 and for locking the nut 10 in rotation. In all of these embodiments, the means brake comprises an electromagnet 18 and a part 19 that is axially movable between a position of locking in rotation of the nut 10 and a position of unlocking in rotation of the nut 10. The locking position of the nut 10 is reached by the moving part 19 under the effect of the electromagnet 18.

In the embodiment of FIGS. 3A and 3B, the nut 10 is mounted on the internal shaft 6 by means of ball or roller screwing, so that the torque for taking up the tangential force by the nut when locking it is greatly reduced. Friction is reduced compared to a thread, and the torque required to lock the nut 10 is reduced.

Moreover, in this embodiment, the axially movable part 19 is coupled to the nut 10. More precisely, the movable part 19 is mounted on the nut 10 so as to slide along a connection 20 at the nut 10 between the two positions of locking and unlocking the rotation of nut 10.

For example, the connection 20 between the axially movable part 19 and the nut 10 is a spline or key connection, the spline 20a being arranged axially on the nut 10, as shown in the , which illustrates a cross-sectional view along the line III-b-III-b of the . The moving part 19 is slidably mounted on this groove 20a. The activation of the electromagnet 18 creates an attractive force on the moving part 19 which can then slide along the link 20 so as to approach the electromagnet 18.

Moreover, in the embodiment of and 3B, the braking means 12 and blocking the rotation of the nut 10 comprises a stop element 21 fixed. The stop element 21 is arranged axially at the connecting end 20 and extends radially so as to be located on the rotation path of the movable part 19 in the blocking position. For example, the abutment element 21 is a brake lining. Thus, during the activation of the electromagnet 18, the movable part 19 moves along the connection 20 towards the electromagnet 18, and is then blocked in translation by the stop element 21, which produces an effect friction leading to the braking and immobilization in rotation of the nut 10. The movable part 19 is therefore then in the position of blocking in rotation of the nut 10.

There represents a second embodiment of the means 12 for braking in rotation and for locking the nut 10.

In this embodiment, the braking and locking means 12 comprises at least one ball 22, preferably a set of balls, means for returning the movable part 19 to the initial axial position 23, as well as a cavity 19b of adjustment of the force exerted on the ball 22.

The moving part 19 is secured to a fixed frame with respect to the stator 4. The moving part 19 extends axially and comprises a radially internal surface 19a facing the nut 10. The ball 22 is arranged radially between the internal surface 19a of the moving part 19 and the external surface 10a of the nut 10. More precisely, the ball 22 is in contact with the external surface 10a.

The surface 19a includes the cavity 19b for adjusting the force applied to the ball extending axially and radially deep enough to accommodate the ball 22. More precisely, the cavity 19b is deep enough to avoid the contact of the ball 22 with the inner surface 19a at this cavity 19b. Outside this cavity 19b, the surface 19a is able to be in contact with the ball 22.

The movable part 19 is axially slidably mounted on the frame so that the movable part 19 slides under the effect of the electromagnet 18 so that when the electromagnet is deactivated, the movable part is axially positioned so that the ball 22 is housed in the cavity 19b. Thus, when the electromagnet 18 is deactivated, the surface 19a exerts no force on the ball 22. The moving part 19 is therefore then in the axial unlocking position.

Conversely, when the electromagnet 18 is activated, the attraction exerted by the electromagnet 18 causes the moving part 19 to slide so that the ball 22 is dislodged from the cavity 19b. Thus the ball 22 is in contact with the surface 19a. Surface 19a then compresses ball 22 against nut 10 so that the nut is braked or locked. The moving part 19 is therefore then in the locking position of the nut 10 under the action of the electromagnet 18.

The means for returning to the initial axial position 23 are positioned so as to exert an axial return force on the moving part opposite to the force of attraction exerted by the activation of the electromagnet 18. In this way, when the electromagnet 18 is deactivated, the return means 23 cause the axial sliding of the moving part from the locking position in which the ball 22 is compressed by the surface 19a to the unlocking position in which the ball 22 is housed in the cavity 19b. Thus, the braking is effective only when the electromagnet 18 is activated.

There illustrates a third embodiment of the rotation braking and locking means 12 of the nut 10.

In this embodiment, the braking and locking means 12 comprises at least one ball 24, preferably a set of balls, return means in the axial position (not shown), friction linings 25, a cavity 26 of adjustment of the force exerted on the ball 24 and the means 27 for moving the ball in the cavity.

Ball 24 is permanently located in cavity 26.

The cavity 26 has a variable axial depth and comprises two axial walls 26a and 26b facing each other and jointly exerting a compressive force on the ball 24. The ball 24 is radially movable in the cavity 26 so that the force exerted on the ball 24 by the walls 26a and 26b of the cavity is variable according to the axial depth of the cavity 26, between the walls 26a and 26b.

The friction linings 25 are arranged axially between a thrust element 30 and a side surface 31 of the nut 10. The thrust element 30 comprises the wall 26a of the cavity 26. The friction linings 25 can for example be braking discs.

The moving part 19 slides axially on a frame linked to the stator 4 between the thrust element 30 and the means 27 for moving the ball in the cavity.

The means 27 for moving the ball in the cavity is arranged axially between the electromagnet 18 and the moving part 19, more precisely between a fixed element 32 linked to the stator 4 and the moving part 19 so that the activation of the electromagnet 18 causes the moving part 19 to move towards the electromagnet so as to compress the moving means 27. The compression of the moving means 27 against the fixed element 32 linked to the frame causes the ball 24 to move radially in the cavity 26 so that the activation of the electromagnet moves the ball 24 into a shallower portion of the cavity 26.

Thus, the ball 24 undergoes a greater compression force. When the ball 24 is thus compressed in the cavity 26, the ball 24 exerts a thrust force on the friction linings 25 through the intermediary of the wall 26a. Thus, the blocking position of the movable part 19 obtained by activation of the electromagnet 18 corresponds to a thrust exerted by the ball 24 on the friction linings 25 against the nut 10. The friction linings 25 then apply a force to the nut 10, and more precisely on the side surface 31 of the nut 10 so as to cause the braking or blocking of the nut 10. In addition, the unlocking position of the movable part 19 corresponds to an insufficient thrust or non-existent exerted by the ball 24 on the friction linings 25 to obtain the braking of the nut 10.

In a final embodiment of the rotation braking and blocking means 12, the electromagnet 18 is mounted on the internal shaft 6 in the vicinity of the nut 10. The electromagnet comprises two opposite polarities and arranged radially opposite the one from the other on the shaft 6 so as to be separated by a recess. This radial recess is intended to receive a portion of a shoulder in rotation of the nut 10, so that the rotation of the nut 10 when the electromagnet 18 is activated causes braking by eddy currents.

Claims (9)

Device for disconnecting (2) a generator (1), comprising an internal shaft (6) mounted axially movable between an engagement position in which the internal shaft (6) is coupled to a drive rotor (5) and a disengagement position in which the internal shaft (6) is disengaged from the drive rotor (5), the disconnection device (2) comprising means for braking and locking in rotation (12) of a nut ( 10) mounted axially immobile on the internal shaft (6), the axial displacement of the internal shaft (6) being caused by the means for braking and locking in rotation (12) of the nut, the braking means and for locking the nut in rotation (12) comprising an electromagnet (18), the disconnection device (2) comprising automatic locking means (13) and unlocking means (14) controlled remotely from the disengaged position of the internal shaft (6). Device according to Claim 1, in which the electromagnet (18) is mounted on the internal shaft (6) and comprises two opposite polarities and arranged facing each other so as to be radially separated by a recess intended to receive a shoulder of the nut (10). Device according to Claim 1, in which the means (12) for braking and locking the nut in rotation (12) comprises an axially movable part (19) between a position for locking the rotation of the nut (10) and a position of unlocking, the locking position being reached under the effect of the activation of the electromagnet (18). Device according to Claim 3, in which the axially movable part (19) is coupled to the nut (18), the means for braking and blocking the nut in rotation (12) comprising an abutment element able to block a rotation of the movable part (19) when the movable part (19) is in the position for blocking the rotation of the nut (10). Device according to Claim 4, in which the nut (10) is coupled to the internal shaft by ball or roller screwing. Device according to Claim 3, in which the braking and rotation-blocking means (12) comprises at least one ball (22, 24) and a cavity (19b, 26) for adjusting the force exerted on the ball, the ball (22, 24) being able to be placed in the cavity (19b, 26), the locking position corresponding to an increased force exerted on the ball (22, 24) and the unlocking position corresponding to a reduced force exerted on the ball (22, 24). Device according to Claim 6, in which the movable part (19) comprises a surface (19a) in contact with the ball (22), the surface (19a) comprising the cavity (19b), the ball (22) being arranged between the surface (19a) of the movable part (19) and the nut (10) so that the ball (22) is housed in the cavity (19b) when the movable part (19) is in the unlocked position, and that the ball (22) is compressed by the surface (19a) of the movable part (19) when the movable part (19) is in the locking position. Device according to Claim 6, in which the means for braking and locking the nut (12) in rotation comprises friction linings (25), the ball (24) being placed in the cavity (26), the cavity being of variable depth, the axially movable part (19) being capable of activating a means (27) for moving the ball in the cavity (26) under the effect of the activation of the electromagnet (18), the position of locking corresponding to a thrust exerted by the ball (24) on the friction linings (25) against the nut (10) and the unlocking position corresponding to an absence of thrust exerted by the ball (24) on the friction linings (25). Assembly comprising a motor and a generator, the motor driving the generator by its shaft in rotation, the generator being equipped with a disconnection device according to one of claims 1 to 8.