Electromechanical actuator capable of realizing fault isolation

Abstract

The invention provides an electromechanical actuator capable of achieving fault isolation. The electromechanical actuator comprises a shell, a transmission part, a lead screw locking nut, a lead screw supporting bearing, a ball screw, a sliding bearing, an actuating rod, an electromagnet, a movable connecting key, a ball nut and a motor. By switching the current direction of the electromagnet, the movable connecting key is driven to move up and down, and mutual connection between the ball nut and the actuating rod can be disconnected. Compared with the prior art, a switching interface is provided for rigid connection between the actuating rod and the transmission part, the rigid connection can be switched into a free state, the rigid connection between the output rod and the transmission part is disconnected when a fault occurs, follow-up work is achieved, fault isolation is achieved, and the reliability of a system can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of aerospace equipment, and in particular relates to an electromechanical actuator with redundant working fault isolation of multiple actuators. Background Art

[0002] Electromechanical actuators are increasingly used in the servo field because of their advantages such as high transmission accuracy, fast response speed, no pollution, and easy use and maintenance. However, their application is limited in situations where reliability is required to be high. The core transmission components (ball screws, roller screws, etc.) of existing electromechanical actuators are at risk of getting stuck or stuck, and they cannot work in a follow-up manner when a fault occurs, which will affect the normal operation of the entire system and is a single point of failure. In order to improve the reliability of electromechanical actuators, a redundant design solution needs to be adopted. However, the current structure of electromechanical actuators cannot work in a follow-up manner, and it is also impossible to achieve redundant operation of multiple actuators. This requires an electromechanical actuator that can work reliably under normal working conditions and work in a follow-up manner when a fault occurs.

[0003] For example, Chinese patent CN112253571B, named as an electromechanical actuator that realizes full-scale, non-full-scale or follow-up functions after the screw is stuck, is composed of an electromechanical actuator and a series hydraulic actuator in series. During normal operation, the hydraulic actuator unit needs to be kept at zero position, so the hydraulic energy source needs to be started, which will make the efficiency of the actuator very low; when the hydraulic actuator unit fails, the actuator cannot work normally, and the reliability of the actuator is low. For example, Chinese patent CN112460220B, named as a fail-safe damping anti-jamming electromechanical actuator. It is composed of a rotatable single ear assembly, a damping actuator cylinder assembly, an unlocking motor assembly, a gear ring assembly, etc. This actuator structure cannot adjust the zero position length of the actuator; a steel ball is used to realize the connection between the ball nut and the actuator cylinder. When the load force is large, the steel ball will be pressed into the blind hole and cannot work normally. Summary of the invention

[0004] The purpose of the present invention is to solve the problems existing in the prior art and to provide an electromechanical actuator capable of achieving fault isolation. When a fault occurs in the transmission part, the rigid connection between the actuating rod and the transmission part is disconnected, and the actuating rod follows the movement to achieve fault isolation.

[0005] The present invention provides an electromechanical actuator capable of realizing fault isolation. The electromechanical actuator comprises: a housing, a transmission part, a screw locking nut, a screw support bearing, a ball screw, a sliding bearing, an actuating rod, an electromagnet, a movable connecting key, a ball nut and a motor.

[0006] Furthermore, the ball screw is installed on the housing through a screw support bearing and a screw locking nut. The power generated by the motor is transmitted to the ball screw through a key connection via the transmission part to output torque and rotation speed, which is converted into linear reciprocating motion of the ball nut through the ball screw pair. The electromagnet is fixed to the actuator rod by screws, the movable connecting key is made of permanent magnet, and the ball nut is made of precipitation-hardened stainless steel. When the electromagnet is not energized, the movable connecting key is adsorbed on the ball nut.

[0007] Furthermore, a compression spring can be added between the movable connecting key and the electromagnet to make the movable connecting key fit tightly on the ball nut. At this time, the movable connecting key limits the relative movement between the ball nut and the actuator rod, and the reciprocating linear motion of the ball nut can be transmitted to the actuator rod. At this time, the electromechanical actuator works normally, outputs linear motion and force, and the sliding bearing plays the role of supporting the actuator rod.

[0008] Furthermore, the electromagnet can generate forces in two directions on the movable connecting key (permanent magnet) by switching the direction of the current: when the force is a repulsive force, the movable connecting key can be pressed against the ball nut; when the force is an attractive force, the movable connecting key can be separated from the ball nut, and the relative movement between the ball nut and the actuator rod is not restricted.

[0009] Furthermore, in order to ensure that the movable connection key can be quickly and reliably separated from the ball nut, the two end faces of the movable connection key are designed as inclined surfaces. In order to ensure the reliability and stability of the transmission, the two end faces of the ball nut and the actuating rod are also designed as inclined surfaces that match the movable connection key.

[0010] The undisclosed technologies in the present invention are common knowledge to those skilled in the art.

[0011] The beneficial effects of the present invention are as follows:

[0012] 1. The present invention can disconnect the mutual connection between the ball nut and the actuating rod by switching the current direction of the electromagnet to drive the up and down movement of the movable connecting key. Compared with the prior art, the present invention provides a switching interface for the rigid connection between the actuating rod and the transmission part, which can realize the switching from the rigid connection to the free state.

[0013] 2. Under the existing technical state, the various parts of the electromechanical actuator are rigidly connected. When a fault occurs, the fault isolation cannot be achieved, which will affect the normal operation of the entire system and is a single point failure. The present invention can disconnect the rigid connection between the output rod and the transmission part when a fault occurs, and work in a follow-up manner to achieve fault isolation.

[0014] 3. The present invention is applicable to the occasions where multiple actuators work redundantly. When a fault occurs, the actuator can work in a follow-up manner without affecting the normal operation of other normal actuators, which can greatly improve the reliability of the system. This advantage makes it have broad application prospects in the fields of auxiliary flight control surfaces of civil aircraft, auxiliary flight control surfaces of fighter aircraft, engine thrust vector control, flight control surfaces of reusable aircraft that can travel between the earth and the sky, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention:

[0016] Figure 1 is a cross-sectional view of an electromechanical actuator according to an embodiment of the present invention;

[0017] Figure 2 is a partial cross-sectional view of an electromechanical actuator according to an embodiment of the present invention;

[0018] Figure 3 is a cross-sectional view of a disengaged state of an electromechanical actuator according to an embodiment of the present invention;

[0019] Figure 4 is a partial cross-sectional view of a disengaged state of an electromechanical actuator according to an embodiment of the present invention;

[0020] Figure 5 is a schematic diagram of the structure of the movable connection key of an embodiment of the present invention;

[0021] Figure 6 It is a schematic diagram of the force of the movable connecting key of the embodiment of the present invention.

[0022] Among them: 1-housing 2-transmission part 3-screw locking nut 4-screw support bearing 5-ball screw 6-sliding bearing 7-actuating rod 8-electromagnet 9-movable connecting key 10-ball nut 11-motor DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0024] This embodiment provides an electromechanical actuator capable of achieving fault isolation. Figure 1 , 2As shown, the electromechanical actuator comprises: a housing 1, a transmission part 2, a screw locking nut 3, a screw support bearing 4, a ball screw 5, a sliding bearing 6, an actuating rod 7, an electromagnet 8, a movable connecting key 9, a ball nut 10, and a motor 11.

[0025] Furthermore, the ball screw 5 is installed on the housing 1 through the screw support bearing 4 and the screw locking nut 3. The power generated by the motor is transmitted to the ball screw 5 through the transmission part 2 through a key connection to output the torque and speed, and is converted into a linear reciprocating motion of the ball nut 10 through the ball screw pair. The electromagnet 8 is fixed to the actuator rod 7 by screws, the movable connecting key 9 is made of permanent magnets, and the material of the ball nut 10 is precipitation-hardened stainless steel. When the electromagnet 8 is not energized, the movable connecting key 9 is adsorbed on the ball nut 10.

[0026] Furthermore, a compression spring can be added between the movable connecting key 9 and the electromagnet 8 so that the movable connecting key 9 fits tightly on the ball nut 10. At this time, the movable connecting key 9 limits the relative movement between the ball nut 10 and the actuating rod 7, and the reciprocating linear motion of the ball nut 10 can be transmitted to the actuating rod 7. At this time, the electromechanical actuator works normally, outputs linear motion and force, and the sliding bearing 6 plays the role of supporting the actuating rod 7.

[0027] Furthermore, the electromagnet 8 can generate two-directional forces on the movable connecting key 9 by switching the current direction: when the force is a repulsive force, the movable connecting key 9 can be pressed against the ball nut 10, and when the force is an attractive force, the movable connecting key 9 can be separated from the ball nut 10, such as Figure 3 , 4 As shown, at this time, the relative movement between the ball nut 10 and the actuating rod 7 is not restricted.

[0028] Furthermore, in order to ensure that the movable connecting key 9 can be quickly and reliably separated from the ball nut 10, the two end faces of the movable connecting key 9 are designed as inclined surfaces, and its appearance is as follows: Figure 5 In order to ensure the reliability and stability of the transmission, the two end surfaces of the ball nut 10 and the actuating rod 7 are also designed to be inclined surfaces that match the movable connecting key.

[0029] like Figure 6As shown, it is a schematic diagram of the force of the movable connecting key 9 of the present invention during the transmission of linear motion, wherein α is the angle between the end face and the horizontal plane, F1 and F2 are the positive pressures received when transmitting linear motion, which can be decomposed into the x and y directions. The component force in the y direction will cause the movable connecting key to detach from the ball nut 10, and the α angle should be less than 90°. The smaller the α angle, the easier it is to detach. However, the component force in the y direction generated during operation is greater, and a greater force is required during operation to make the movable connecting key 9 reliably and tightly fit on the ball nut 10. In order to make the electromechanical actuator have a greater bearing capacity, the α angle should be selected to be a larger value, generally 85°≤α<90°, and the magnetism of the electromagnet 8 should be strong.

[0030] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electromechanical actuator capable of achieving fault isolation, characterized in that: include: A housing (1), a transmission part (2), a screw locking nut (3), a screw support bearing (4), a ball screw (5), a sliding bearing (6), an actuating rod (7), an electromagnet (8), a movable connecting key (9), a ball nut (10), and a motor (11); when a failure occurs in the transmission part (2), the rigid connection between the actuating rod (7) and the transmission part (2) can be disconnected, and the actuating rod (7) can work in a follow-up manner; wherein, The ball screw (5) is mounted on the housing (1) via a screw support bearing (4) and a screw locking nut (3); the power generated by the motor is transmitted to the ball screw (5) via a key connection via a transmission part (2) to generate an output torque and a rotation speed, which is then converted into a linear reciprocating motion of a ball nut (10) via the ball screw (5); The electromagnet (8) is fixed to the actuating rod (7) by means of screws; By controlling the electromagnet (8) to turn on or off power or switching the current direction of the electromagnet (8), the movable connection key (9) is driven to move up and down, thereby controlling the mutual connection or disconnection between the ball nut (10) and the actuating rod (7); The sliding bearing (6) plays a role in supporting the actuating rod (7).

2. The electromechanical actuator capable of achieving fault isolation according to claim 1, characterized in that: The movable connection key (9) is made of a permanent magnet, and the material of the ball nut (10) is precipitation hardened stainless steel. When the electromagnet (8) is not energized, the movable connection key (9) is adsorbed on the ball nut (10).

3. The electromechanical actuator capable of achieving fault isolation according to claim 2, characterized in that: When the electromagnet (8) is not energized, the movable connecting key (9) limits the relative movement between the ball nut (10) and the actuating rod (7), and the reciprocating linear motion of the ball nut (10) can be transmitted to the actuating rod (7). At this time, the electromechanical actuator works normally and outputs linear motion and force.

4. The electromechanical actuator capable of achieving fault isolation according to claim 1, characterized in that: The electromagnet (8) can generate forces in two directions on the movable connection key (9) by switching the direction of the current.

5. The electromechanical actuator capable of achieving fault isolation according to claim 4, characterized in that: When the force between the electromagnet and the movable connecting key is a repulsive force, the movable connecting key (9) is pressed against the ball nut (10). When the force is an attractive force, the movable connecting key (9) is separated from the ball nut (10). At this time, the relative movement between the ball nut (10) and the actuating rod (7) is not restricted.

6. The electromechanical actuator capable of achieving fault isolation according to claim 1, characterized in that: A compression spring is arranged between the movable connection key (9) and the electromagnet (8), and when the electromagnet is not energized, the movable connection key (9) is tightly fitted on the ball nut (10).

7. The electromechanical actuator capable of achieving fault isolation according to claim 1, characterized in that: The two side end faces of the movable connection key (9) are designed as inclined surfaces, and the two end faces of the ball nut (10) and the actuating rod (7) are also correspondingly designed as inclined surfaces matching the movable connection key (9), thereby ensuring smooth and reliable transmission.

8. The electromechanical actuator capable of achieving fault isolation according to claim 7, characterized in that: The included angle between the end faces on both sides of the movable connection key (9) and the horizontal plane is α, and 85°≤α<90°.

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