Electric motor

Abstract

The present invention relates to an electric motor, particularly for driving an electromechanical actuator, comprising: a stator, and a rotor, which can rotate relative to the stator, characterized in that a socket, in particular a burst socket, is provided, a peripheral wall of the socket being disposed in an intermediate space formed between the stator and the rotor and surrounding at least in places the stator located inside or the rotor located inside. Fig. 1

Description

Title of the invention: Electric motor

[0001] The present invention relates to an electric motor, in particular an electric motor with anti-jamming protection, as well as an aircraft with an electric motor of this type.

[0002] The present invention relates to an electric motor, which is equipped to prevent the electric motor from jamming.

[0003] In the modern aeronautical sector, reliability and safety are of paramount importance, particularly in safety-critical applications such as helicopter fly-by-wire controls. Electric motors play a central role in controlling and moving actuators, which either actuate control valves or directly produce the necessary control force. A failure or blockage of the electric motor can lead to serious malfunctions that threaten the safety of the aircraft and its passengers.

[0004] According to the prior art, various approaches are used to minimize the risk of motor seizure. For example, several electric motors can be connected in series, with their rotors mounted on a common shaft. Each rotor is connected to the shaft by an individual coupling to allow for the disconnection of individual motors in the event of a malfunction. The common shaft controls the fluid flow to hydraulic control cylinders via two individual spool valves. Structures of this type are known, for instance, from the NH90 helicopter. Although these assemblies are functional, they have considerable drawbacks. Their structure is complex, and their production and maintenance are cumbersome and expensive.

[0005] Another approach based on the prior art involves using two completely independent control systems, with only one active and a switchover to the second in case of malfunction. However, these systems significantly increase complexity and cost, as they must be fully redundant. Furthermore, fault identification is particularly demanding because, in the highly dynamic environment of a helicopter, a malfunction must be identified reliably and quickly enough to avoid major transient effects that could compromise the stability and control of the aircraft.

[0006] The aforementioned drawbacks of the current state of the art lead to several problems. The high complexity and additional weight impact the efficiency and performance of the electric motor or of an aircraft using the motor electrical. High costs complicate the profitability of the systems, and challenges in identifying faults quickly and safely can compromise reliability.

[0007] Consequently, the present invention aims to provide a simplified, lighter, and more economical solution that nevertheless meets the highest safety standards. The invention must also be able to optimize the Direct Drive Valve (DDV) concept, as used, for example, in the NH90 helicopter, in that it minimizes the risk of an electric motor seizing up, or even eliminates it in the best-case scenario. In the case of a valve assembly operating according to the DDV principle in a hydraulic or pneumatic system, conventional intermediate components, such as mechanical gears or hydraulic amplifiers, are omitted. Instead, a valve spool is directly driven by an electric motor or actuator.

[0008] Naturally, those skilled in the art are aware that the invention is not limited to use in aircraft such as helicopters and the like. It can be used in all applications where locking the electric motor is critical from a safety standpoint or is detrimental. This includes, for example, other areas of aeronautics, the automotive industry, or industrial control systems.

[0009] The present invention aims to provide a flexible and reliable solution that meets the stringent requirements of various safety-critical applications. This is achieved with an electric motor according to the invention.

[0010] The electric motor according to the invention, in particular an electric motor intended to drive an electromechanical actuator, comprises a stator and a rotor, which can rotate relative to the stator. The electric motor is characterized in that a socket, in particular a burst socket, is provided, a peripheral wall of the socket being disposed in an intermediate space formed between the stator and the rotor and enclosing at least in places the stator located inside or the rotor located inside.

[0011] The invention therefore provides a sleeve, which protects the component located inside the motor, i.e. either the stator or the rotor, from the component located outside the motor so that a blockage does not directly cause a blocking effect between the stator and the rotor, but rather a blockage with the sleeve so that a second plane of motion has been created which prevents the blockage of the stator and the rotor.

[0012] Moreover, it is obvious to a person skilled in the art that the underlying idea of ​​the invention can be applied in both an external armature and an internal armature and it is only important to provide a wall of the sleeve in the air gap formed between the stator and the rotor to avoid the blockage occurring in the event of a blockage normally occurring between the stator and the rotor.

[0013] The realization of at least one component of the electric motor or the identification unit such that the torque produced by the surface coupling or the spring centering is used to identify a blockage.

[0014] An improvement in variant of the present invention makes it possible to provide that the bushing is fixed on the stator or rotor by an anti-rotation locking system to prevent any rotation on the stator or on the rotor, the anti-rotation locking system ensuring rotation only until a threshold value of rotational torque is reached between the bushing and the stator or rotor, on which the bushing is fixed and allows, in the event of exceeding the threshold value of rotational torque, rotation relative to the stator or the rotor.

[0015] Thus, it is also provided that the sleeve is arranged either on the rotor or on the stator by means of an anti-rotation locking system, which rigidly fixes the sleeve against rotation with respect to a rotational torque, the direction of which extends substantially radially with respect to the axis of rotation of the electric motor or the rotor. It is only in the presence of a rotational torque acting on the sleeve, the value of which exceeds the rotational torque threshold value, that the anti-rotation locking system leaves its fixed position relative to the element (rotor or stator) to which it was rigidly connected before the rotational torque threshold value was exceeded, so that rotation of the sleeve relative to the previously immobilized element (rotor or stator) of the electric motor can be induced.

[0016] Therefore, if no or only an action force less than the threshold value of rotational torque acts on the bushing, the bushing is connected in a fixed rotational manner to the stator or rotor, the fixed rotational connection being abandoned if a rotational torque exceeding the threshold value of rotational torque were to act on the bushing.

[0017] It may be provided in this context that the anti-rotation locking system comprises or is a burst coupling, an overload coupling, a shear coupling, in particular in the form of a shear pin and / or a spring centering device. All these configurations ensure that the bushing is fixed in rotation on the stator or rotor of the electric motor until a threshold torque value is reached and that it is released after exceeding the threshold torque value so that the bushing can then rotate freely also relative to the element (rotor or stator) on which it was initially fixed in rotation.

[0018] Another advantageous configuration of the present invention allows the bushing to be mounted with at least one bearing relative to the rotor and / or relative to the stator, in particular at least one bearing being a plain bearing, a ball bearing and / or a roller bearing.

[0019] The bearing, with which the bushing is mounted relative to the rotor and / or the stator, serves to allow the bushing to rotate around the axis of rotation of the rotor or stator of the electric motor. Similar to an inner armature, in which the rotor is surrounded by the stator on its peripheral side, this means that the bushing, fixed to the rotor by means of the anti-rotation locking system, is mounted relative to the stator in such a way that a similar rotational movement of the rotor and a bushing fixed to it can be achieved in accordance with the operating principle of the electric motor. Therefore, as long as the rotational torque acting on the bushing or the anti-rotation locking system is less than the rotational torque threshold value, the bushing rotates with the rotor.

[0020] An improvement in variant of the present invention makes it possible to provide that the bushing is mounted between an inner bearing and an outer bearing, the inner bearing and the outer bearing being preferably arranged in an offset manner relative to each other in the radial direction towards the rotor.

[0021] Due to the provision of two bearings arranged in a staggered fashion relative to each other in the radial direction of the electric motor, between which the bushing is mounted, the functionality of the electric motor is maintained simply when a torque lower than the rotational torque threshold value acts on the bushing, insofar as, like a rotor surrounded by the bushing, it can rotate in conjunction with the bushing. The bushing is thus mounted on the stator, which in this example surrounds the rotor, via the bearing arranged radially on the outside (such as a ball bearing, plain bearing, and / or roller bearing).The bearing arranged radially inside for this purpose, in particular the plain bearing, ball bearing and / or roller bearing, supports the bushing relative to the rotor and is then used as intended when the rotational torque acting on the bushing exceeds the torque threshold value. Finally, this results in the anti-rotation locking system releasing the bushing so that it can also rotate relative to the previously fixed element (in this case, the rotor).

[0022] If this configuration then results in a blockage due to an element entering the slot between the bushing and the stator, a force exceeding the rotational torque threshold value acts on the anti-rotation locking system, such that the previously rotationally fixed connection between the rotor and the bushing is released. The primary function of the motor can then continue to be performed insofar as the capacity for movement between the rotor and the stator is maintained, since the blocking event only ensures that the bushing is held against the stator; the rotor can However, it would continue to rotate. Without the sleeve in the slot between the stator and the rotor, the clamping event would limit the movement capacity of the stator and rotor to such an extent that rotation of the rotor relative to the stator would no longer have been possible.

[0023] An advantageous modification of the present invention makes it possible to provide that the inner bearing and the outer bearing also serve to support the rotor relative to the stator.

[0024] The use of the burst sleeve to identify a ball bearing blockage is feasible insofar as, due to the blockage of the burst sleeve, only one bearing is always in motion. If this bearing were to block, the overload coupling / spring centering mechanism is also activated, thus allowing the identification of said failure as defined above. The burst sleeve can therefore also be used to identify a bearing blockage.

[0025] An advantageous configuration also allows for the inner and outer bearings, spaced apart in the radial direction, to be at the same height in the longitudinal direction of the rotor. This ensures a particularly stable configuration of the present invention, since the bushing is then supported at the same height by two bearings spaced apart in the radial direction. However, it is obvious to those skilled in the art that there may be several inner and outer bearings that provide support for the bushing relative to the stator and / or the rotor.

[0026] Another improvement of the present invention allows the socket to be made of a non-magnetic material, in particular a non-magnetic metallic material, such as titanium or aluminum, or a composite material, such as carbon, or a thermoplastic synthetic material, for example PEEK (polyetheretherketone).

[0027] Insofar as the rotation of the rotor is carried out by the creation of a magnetic field in the slot between the rotor and the stator, the fact that the sleeve disposed in said slot influences the magnetic field as little as possible and is made of a non-magnetic material is advantageous.

[0028] Consequently, the invention may further provide that the socket is disposed in the air gap of the electric motor formed between the stator and the rotor and encloses at least in places or totally either the stator or the rotor.

[0029] Furthermore, an improvement to the present invention allows the inner and outer bearings to be positioned in the same way in the longitudinal direction of the rotor, but are offset from each other in the radial direction of the rotor. Typically, the bushing is housed and held between the two bearings, which are offset in the radial direction.

[0030] An advantageous configuration of the present invention makes it possible to foresee that the electric motor is a rotational motor with a limited angle of rotation.

[0031] An advantageous modification of the present invention also allows the electric motor to be provided as an internal armature, for which the stator surrounds the rotor on the periphery side.

[0032] An alternative modification of the present invention allows the electric motor to be provided as an external armature, for which the rotor surrounds the stator on the peripheral side.

[0033] The invention further relates to a hydraulic adjustment drive with an electric motor according to one of the aspects discussed previously, the electric motor being intended to actuate a hydraulic control valve in the hydraulic adjustment drive.

[0034] Moreover, the present invention also relates to an electromechanical actuator, in particular intended to perform a primary flight control of an aircraft, with an electric motor according to one of the aspects discussed previously, the electric motor being intended to actuate the electromechanical actuator.

[0035] The present invention also relates to an aircraft with an electric motor according to one of the aspects discussed above or a hydraulic adjustment drive according to one of the aspects discussed above, the aircraft preferably being an airplane, in particular a military airplane, or a helicopter.

[0036] Other features, details and advantages of the invention will become apparent from the description in the following figures, which show: [Fig.1]: a schematic representation of an electric motor according to the invention, and [Fig.2]: a schematic representation of an electric motor according to the invention with a position sensor disposed on a rotor.

[0037] Figure 1 illustrates a schematic representation of the electric motor 1 according to the invention, in which the stator 2 surrounds the rotor 3 located inside on its peripheral side. Furthermore, it can be seen that a socket 4, which is disposed by a wall 5 in the slot 6, is provided in the slot 6 between the stator 2 and the rotor 3.

[0038] The sleeve 4 can be disposed by its cylindrical enveloping surface in the peripheral slot and has on its respective longitudinal ends a section extending radially inwards, on which the anti-rotation locking system 7 or the support is fixed relative to the stator 2 and the rotor 3.

[0039] It can also be seen that the bushing 4 is supported between an inner bearing 8 and an outer bearing 9, the inner bearing 8 being offset relative to the rotor 3 in the radial direction relative to the outer bearing 9. The anti-rotation locking system 7 connects the rotor 3 to a section of the bushing 4 in this case, although a mounting on the stator 2 is also potentially conceivable. The anti-rotation locking system 7 rigidly holds the bushing 4 onto the rotor 3 until a rotational torque exceeding the torque threshold value acts on the bushing 4, at which point the anti-rotation locking system opens and allows the bushing to rotate relative to the rotor. An example of such an anti-rotation locking system is an overload coupling, a burst coupling, or an anti-burst locking system (such as a shear pin or similar), which breaks when the torque threshold value is exceeded.

[0040] If a blockage then occurs in the space between the stator 2 and the wall 5 of the sleeve 4, the rotational torque acting on the sleeve 4 increases beyond the rotational torque threshold value, such that the anti-rotation locking system 7 no longer maintains the clamping force on the rotor 3. The clamping event therefore does not prevent relative movement between the stator 2 and the rotor 3, but instead only blocks the movement of the sleeve 4 relative to the stator 2. Insofar as, after exceeding the rotational torque threshold value, the anti-rotation locking system 7 releases its previous rotational hold of the sleeve on the rotor 3, the rotor 30 can move relative to the sleeve 4, thus ensuring the functionality whereby the rotor 3 can move relative to the stator 2.The clamping event therefore does not ensure a fixed positioning of the rotor 3 and the stator 2, but rather, for example, a bursting of an anti-rotation locking system 7 implemented as an anti-burst locking system or shear pin. The bushing, together with the anti-rotation locking system 7, produces, if necessary, an alternative plane of motion such that the clamping event cannot cause a stoppage or slowing of the relative motion between the stator 2 and the rotor 3.

[0041] The anti-rotation locking system 7 can thus be configured in such a way, for example in the form of an overload coupling or similar, that a permanent counter-torque acting against the direction of rotation of the motor (braking) is produced after the threshold value of the rotational torque is exceeded, with the effect that an electric motor control is able to identify said state of the electric motor 1 and conclude that a locking event has occurred. The identification of such an anomaly is typically carried out via the motor current made available for the control of the electric motor.

[0042] Fig. 2 illustrates an embodiment of the electric motor 1 according to the invention, in which the position of the rotor 3 can be defined by means of a position sensor 10.

[0043] The position sensor 10 is attached in this frame to the rotor 3 by means of an anti-burst locking system 11. The position of the rotor 3 can be set in this frame by an LVDT (linear variable differential transformer), the anti-burst locking system attaching the position sensor 10 to the rotor 3 also ensuring that here a blockage of an individual sensor does not also cause a deficiency of the electric motor 1.

[0044] List of reference numbers 1 - Electric motor 2 - Stator 3 - Rotor 4 - Socket 5 - Socket wall 6 - Intermediate space between the stator and the rotor 7 - Anti-rotation locking system 8 - Interior landing 9 - Exterior landing 10 - Position sensor 11 - Anti-burst locking system

Claims

Demands

1. Electric motor (1), intended in particular to drive an electromechanical actuator, comprising: a stator (2), and a rotor (3), which can rotate relative to the stator (2), characterized in that a sleeve (4), in particular a burst sleeve, is provided, in which a peripheral wall (5) of the sleeve (4) is disposed in an intermediate space (6) made between the stator (2) and the rotor (3) and encloses at least in places the stator (2) located inside or the rotor (3) located inside.

2. Electric motor (1) according to the preceding claim 1, wherein the bushing (4) is fixed on the stator (2) or the rotor (3) by means of an anti-rotation locking system (7) to prevent any rotation of the bushing (4) on the stator (2) or on the rotor (3), wherein the anti-rotation locking system (7) ensures rotation only when a threshold value of rotational torque between the bushing (4) and the stator (2) or the rotor (3), on which said bushing (4) is fixed, is reached, and permits rotation relative to the stator (2) or the rotor (3) when said threshold value of rotational torque is exceeded.

3. Electric motor (1) according to the preceding claim 2, wherein the anti-rotation locking system (7) comprises or is a burst coupling, an overload coupling, a shear coupling, in particular in the form of a shear pin, and / or a spring centering.

4. Electric motor (1) according to claim 2 or 3, wherein the electric motor is designed to use the torque generated by the overload coupling or spring centering to identify a blockage.

5. Electric motor (1) according to any one of the preceding claims, wherein the bushing (4) is supported with a bearing (8, 9) relative to the rotor (3) and / or relative to the stator (2), wherein the bearing (8, 9) is a plain bearing, a ball bearing and / or a roller bearing.

6. An electric motor (1) according to any one of the preceding claims, wherein the bushing (4) is supported between an inner bearing (8) and an outer bearing (9), preferably wherein the inner bearing (8) and the outer bearing (9) are arranged in such a way offset from each other in the radial direction relative to the rotor (3).

7. Electric motor (1) according to the preceding claim 6, wherein the inner bearing (8) and the outer bearing (9) also serve to support the rotor (3) relative to the stator (2).

8. Electric motor (1) according to any one of the preceding claims, wherein the burst sleeve is also used to identify a blockage of a ball bearing.

9. Electric motor (1) according to any one of the preceding claims, wherein the bushing (4) is made of a non-magnetic material, in particular a non-magnetic metallic material, such as titanium or aluminum, or a composite material, such as carbon, or a thermoplastic synthetic material, such as PEEK.

10. Electric motor (1) according to any one of the preceding claims, in which the bushing (4) is disposed in the air gap (6) of the electric motor (1) formed between the stator (2) and the rotor (3) and encloses at least in places or entirely either the stator (2) or the rotor (3).

11. Electric motor (1) according to claim 6 and any one of the preceding claims, wherein the inner bearing (8) and the outer bearing (9) are provided in the same position in the longitudinal direction of the rotor (3), however are arranged in an offset manner relative to each other in the radial direction of the rotor (3).

12. Electric motor (1) according to any one of the preceding claims, wherein the electric motor (1) is a rotary motor with a limited angle of rotation.

13. Electric motor (1) according to any one of the preceding claims, wherein the electric motor (1) is an internal armature, in which the stator (2) surrounds the rotor (3) on its peripheral side.

14. Electric motor (1) according to any one of the preceding claims 1 to 12, wherein the electric motor (1) is an external armature, in which the rotor (3) surrounds the stator (2) on its peripheral side.

15. Hydraulic adjustment drive with an electric motor (1) according to any one of the preceding claims, in which The electric motor (1) is intended to actuate a hydraulic control valve in the hydraulic adjustment drive.

16. Electromechanical actuator, intended in particular to perform a primary flight control of an aircraft, with an electric motor (1) according to any one of claims 1 to 14, wherein the electric motor (1) is provided to actuate the electromechanical actuator.

17. Aircraft with an electric motor (1) according to any one of the preceding claims 1 to 14 or a hydraulic adjustment drive according to the preceding claim 15, preferably wherein the aircraft is an airplane, in particular a military airplane, or a helicopter.

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