Emergency unlock electromechanical actuator

Abstract

The emergency unlocking electromechanical actuator disclosed by the application has simple structure, compactness, and reliable performance.The application is achieved by the following technical scheme: a servo motor is connected with a disc gear transmission mechanism through a clutch shaft to drive a screw gear to rotate, a screw nut is constrained in a hollow step hole of a piston head through an end cover sliding sleeve, a steel ball lock is locked in a guide groove of the piston head by a locking groove on an inner wall of an outer cylinder, in an emergency, the clutch is disengaged, high-pressure medium enters the outer cylinder cavity through an emergency energy inlet on an outer ring surface of the outer cylinder to form a closed-loop emergency circuit that overcomes the elastic force of the reset spring, the high-pressure medium pushes the front end surface of the end cover sliding sleeve to the limit position of the steel ball lock on the end surface of the hollow step hole of the piston head, the steel ball lock is released from the locking groove, the steel ball lock is unlocked in an emergency, the high-pressure medium pushes the piston rod to drive the screw nut to reversely drive the screw transmission pair to rotate, and at the same time, the piston rod is extended in an emergency, thereby completing the unlocking and the extension of the piston rod.

Description

Technical Field

[0001] This invention relates to an emergency unlocking and extension structure applied to electromechanical actuators; more specifically, this invention relates to an innovative structure that improves the safety and reliability of electromechanical actuators and enables multi-media emergency unlocking and extension of the piston rod. Background Technology

[0002] With the development of modern technology, the mission functions of small or unmanned aircraft have undergone significant development and changes. In emergency situations, aircraft need to land safely to protect advanced and expensive onboard equipment and mission-related equipment. The landing gear of small or unmanned aircraft should have emergency unlocking, safe and rapid deployment, and automatic locking functions. The landing gear retraction system plays a crucial role in aircraft takeoff and landing. Currently, some light aircraft generally use hydraulic retraction systems. This type of system has certain advantages, such as high output force and relatively stable performance. However, its disadvantages are also very obvious, mainly including high energy consumption, long maintenance time, large component weight, and relatively low operating efficiency. Due to the ever-increasing performance requirements of light aircraft, the disadvantages of using hydraulic retraction systems are gradually becoming the main reason restricting the improvement of light aircraft performance. Therefore, it is necessary to strengthen the research and optimization of landing gear electric actuator structures. This type of system mainly uses electricity as the power source for retraction and deployment, and uses the electric actuator as the main execution command element. The main structure of the landing gear electromechanical actuator consists of a pneumatic motor, a pneumatic clutch, a DC motor, a gear reducer, a synchronous belt device, a lead screw and nut pair, a locking mechanism, a piston rod, a ball screw, a piston cylinder, and a micro switch. The electric retraction and extension actuator is controlled by the aircraft's electrical control system. In the event of an emergency such as a malfunction of the electrical control system or damage to the control system equipment, the upper mechanical lock inside the electric retraction and extension actuator will not be able to open, preventing the actuator from lowering. Consequently, the aircraft landing gear cannot be lowered and locked properly, resulting in a serious catastrophic accident. As a linear motion actuator of the aircraft landing gear, the actuator is an energy conversion device used to achieve linear reciprocating motion or less than 360° motion of the working mechanism. The basic components of a common electromechanical actuator are as follows: motor, gearbox, transmission components, ball screw pair, outer cylinder assembly, piston rod assembly, and self-locking assembly. Electromechanical actuators with self-locking devices prevent erratic movement caused by external forces when stopped at a defined position. This is typically achieved through a mechanical lock within the actuator cylinder. The most common type of mechanical lock is a ball-lock, which consists of a ball lock, a locking groove, a conical piston, and a spring. In the event of a power failure or closed-loop position control failure, the rigid collision and compression between the inner end faces of the ball screw pair at the extreme positions of the electromechanical actuator can cause deformation of the ball screw pair's helical raceway, increasing the clearance and reducing the accuracy of the screw transmission. This can even lead to the screw pair jamming, resulting in the loss of the electromechanical actuator's function. Actuators with emergency functions are generally used, but installation space is often very limited. Commonly used actuators include electromechanical and hydraulic actuators. Electromechanical actuators have complex emergency response mechanisms; existing hydraulic actuators have a long axial length, which is inconvenient for installation, and their emergency response mechanisms often rely on pneumatic methods, requiring a dedicated air source.Currently, electromechanical actuators, as transmission mechanisms, function to drive rotation according to commands after being energized. The process from the actuator's motor to the aircraft's control shaft involves deceleration and torque amplification. Therefore, when the actuator is not energized, a corresponding locking device needs to be installed on its motor shaft to provide the required locking torque after deceleration and torque amplification. Since modern aircraft landing gear is typically retractable, usually using hydraulics for normal retraction and extension, if a malfunction occurs in the aircraft's hydraulic or electrical systems, preventing the landing gear from being lowered normally, the aircraft must have a manual emergency landing gear deployment mechanism. Its performance directly affects aircraft safety. However, there have been numerous cases of aircraft landing gear emergency deployment failures, leading to forced landings, highlighting the crucial importance of landing gear emergency deployment systems for ensuring flight safety. In applications with high safety requirements, such as electromechanical actuators used for aircraft landing gear retraction and extension, a certain safety margin is required. Commonly used electromechanical actuator redundancy designs include a backup motor; when the main motor fails, the backup motor operates to achieve emergency deployment or retraction of the piston rod. Conventional dual-redundant electromechanical actuators still rely on electricity for emergency deployment and retraction, posing certain safety hazards, resulting in low safety, low reliability, and poor practicality. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the prior art by providing a solution that is simple in structure, compact, reliable in performance, occupies little space, ensures aircraft flight safety, and does not rely on electricity for emergency unlocking and extension of the piston rod. This effectively solves the problem that conventional dual-redundant electromechanical actuators still rely on electricity for emergency retraction and extension, and enables redundant emergency response for different working media, as well as emergency unlocking of the electromechanical actuator.

[0004] The technical solution adopted by this invention to solve its technical problem is: an emergency unlocking electromechanical actuator, comprising: a gear transmission mechanism connected to the sealed cavity of the outer cylinder 1 of the electromechanical actuator via a servo motor shaft connecting to a gear transmission disc; a lead screw transmission pair 8 assembled in the transmission cavity of the outer cylinder 1 and meshing with the gear transmission mechanism; a piston rod 6 that performs telescopic movement in the outer cylinder 1; and a lead screw nut 7 sealed in the hollow stepped hole of the piston head. The servo motor 11 drives the lead screw gear to rotate via a clutch 12 shaft connecting to the gear transmission disc; the lead screw transmission pair 8 passes through the encapsulated bearing and the hollow threaded raceway of the lead screw nut 7, passing through the spacer ring of the piston rod 6 and pointing to the bottom end of the hollow cavity; the lead screw nut 7, through an end cap sleeve 10 sealed on the end face of the fixed end stepped ring, constrains the return spring 9 in the hollow stepped hole of the piston head; and is fitted onto the lower end of the evenly distributed steel ball locks 4 along the circumference, and the upper locking groove 3 located on the inner wall of the outer cylinder 1 locks the steel ball locks 4 in the guide groove 5 of the piston head. During normal operation, the rotating lead screw drive pair 8 drives the lead screw nut 7, which pushes the end cover sleeve 10 to overcome the spring force of the return spring 9 and disengage from the lower end of the steel ball lock 4 through the step at the tail end of the lead screw nut 7. The steel ball lock 4 rolls radially inward along the guide groove 5 and disengages from the upper locking groove 3, after which the piston rod 6 extends. During emergency operation, the clutch 12 disengages, and a high-pressure medium, which is a dissimilar energy source to electrical energy, enters the outer cylinder 1 cavity through the emergency energy inlet 2 on the outer ring surface of the outer cylinder 1, forming a closed-loop emergency circuit that pushes the end cover sleeve 10 to overcome the spring force of the return spring 9. The high-pressure medium in the closed-loop emergency circuit pushes the front end face of the end cover sleeve 10 to the limit position of the steel ball lock at the end face of the hollow step hole in the piston head. The steel ball lock 4 rolls radially inward along the guide groove 5 and disengages from the upper locking groove 3, thus unlocking the steel ball lock in an emergency. The high-pressure medium pushes the piston rod 6, which drives the lead screw nut 7 to rotate in the opposite direction, and at the same time, the piston rod 6 extends in an emergency. Under the condition of actuator power failure, the unlocking and piston rod extension tasks are completed.

[0005] Compared with the prior art, the present invention has the following advantages:

[0006] This invention employs a gear transmission mechanism connected to the sealed cavity of the outer cylinder 1 of the electromechanical actuator via a shaft connecting disc, a lead screw transmission pair 8 meshing with the gear transmission mechanism and assembled in the transmission cavity of the outer cylinder 1, and a piston rod 6 that performs telescopic movement in the outer cylinder 1. The structure is simple, reliable, and has high mechanical strength, capable of withstanding large stable and dynamic loads. It reduces mechanical vibration, lowers noise, and improves the working environment.

[0007] This invention uses a servo motor 11 to drive a lead screw gear through a clutch 12 shaft-connected disc gear transmission mechanism. The lead screw passes through the hollow threaded raceway of the lead screw nut 7 assembled in the hollow stepped hole of the piston head, passes through the piston rod 6 and points to the bottom of the cavity. The lead screw nut 7 is sealed in the hollow stepped hole of the piston head and is sealed by the end cover sleeve 10 on the end face of the fixed end stepped ring. The return spring 9 is constrained in the hollow stepped hole of the piston head and limited to the inner ring of the steel ball lock 4. The upper locking groove 3 located on the inner wall of the outer cylinder 1 locks the steel ball lock 4 in the guide groove 5 of the piston head. The structure is simple and compact and occupies little space.

[0008] This invention designs corresponding sealing structures for the inner and outer circles of the end cover sleeve 10, so that it can be driven by emergency medium to open the mechanical lock of the electromechanical actuator steel ball lock 4. This ensures that when emergency operation is required, the emergency medium entering the actuator can drive the mechanical lock of the steel ball lock 4 to unlock and extend the piston rod 6, thereby solving the problem that conventional electromechanical actuators do not have multi-medium emergency operation.

[0009] This invention utilizes a high-pressure medium that enters the outer cylinder 1 cavity through the emergency energy inlet 2 on the outer ring surface of the outer cylinder 1. This medium pushes the end cover sleeve 10 to overcome the elastic force of the return spring 9 and disengage from the lower end of the steel ball lock 4, thus mechanically unlocking the steel ball lock 4. The high-pressure medium then pushes the piston rod 6, which in turn drives the lead screw nut 7 to rotate in the reverse direction, causing the lead screw transmission pair 8 to extend. This not only changes the traditional emergency unlocking method of the actuator cylinder and simplifies the control system and structure of the actuator cylinder, but also avoids serious catastrophic accidents caused by the inability to open the mechanical lock inside the actuator cylinder, improving the safety of the landing gear retraction or opening / closing mechanism. Furthermore, by designing corresponding sealing structures for the inner and outer circles of the end cover sleeve 10, it can be driven by the emergency medium to open the mechanical lock of the electromechanical actuator. This ensures that when emergency operation is required, the emergency medium entering the actuator can drive the mechanical lock to unlock and extend the piston rod 6, thereby solving the problem of conventional electromechanical actuators lacking multi-medium emergency operation capabilities.

[0010] This invention employs a high-pressure medium to drive the piston rod 6, which in turn drives the lead screw nut 7 to rotate the lead screw transmission pair 8. Simultaneously, the piston rod 6 extends. Furthermore, in the case of a power failure in the actuator, this invention effectively solves the problem that conventional dual-redundant electromechanical actuators still rely on electricity for emergency retraction and extension. Attached Figure Description

[0011] Embodiments of this application will now be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement this application. However, it should be noted that this application is not limited to the embodiments but can be implemented in many other ways. In the drawings, irrelevant parts of the description have been omitted for brevity, and the same reference numerals denote the same parts throughout.

[0012] Figure 1 This is a schematic diagram of the locked state structure of the emergency unlocking electromechanical actuator of the present invention.

[0013] In the diagram: 1 Outer cylinder, 2 Emergency power inlet, 3 Locking groove, 4 Steel ball lock, 5 Guide groove, 6 Piston rod, 7 Lead screw nut, 8 Lead screw transmission pair, 9 Return spring, 10 End cover sleeve, 11 Servo motor, 12 Clutch.

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this does not limit the invention to the scope of the described embodiments. All these concepts should be considered as the content disclosed in this technology and the scope of protection of this invention. Detailed Implementation

[0015] Reference Figure 1 In the preferred embodiment described below, an emergency unlocking electromechanical actuator includes: a gear transmission mechanism connected to the sealed cavity of the outer cylinder 1 of the electromechanical actuator via a servo motor shaft connecting to a gear transmission disk; a lead screw transmission pair 8 assembled in the transmission cavity of the outer cylinder 1 and meshing with the gear transmission mechanism; a piston rod 6 that performs telescopic movement in the outer cylinder 1; and a lead screw nut 7 that is annularly sealed in the hollow stepped hole of the piston head. The servo motor 11 drives the lead screw gear to rotate via a gear transmission mechanism connected to a clutch 12 shaft. The lead screw transmission pair 8 passes through a sealed bearing and the hollow threaded raceway of the lead screw nut 7, passing through the spacer ring of the piston rod 6 and pointing to the bottom end of the hollow cavity. The lead screw nut 7 is annularly sealed to the end cover sleeve 10 on the end face of the fixed end stepped ring, constraining the return spring 9 in the hollow stepped hole of the piston head. It is fitted onto the lower end of steel ball locks 4 evenly distributed along the circumference. The upper locking groove 3 located on the inner wall of the outer cylinder 1 locks the steel ball locks 4 in the guide groove 5 of the piston head. During operation, the rotating lead screw drive pair 8 drives the lead screw nut 7, which pushes the end cover sleeve 10 to overcome the spring force of the return spring 9 and disengage from the lower end of the steel ball lock 4 through the step at the tail end of the lead screw nut 7. The steel ball lock 4 rolls radially inward along the guide groove 5 and disengages from the upper locking groove 3, at which point the piston rod 6 extends. In emergency operation, the clutch 12 disengages, and a high-pressure medium, which is a dissimilar energy source to electrical energy, enters the outer cylinder 1 cavity through the emergency energy inlet 2 on the outer ring surface of the outer cylinder 1, forming a closed-loop emergency circuit that pushes the end cover sleeve 10 to overcome the spring force of the return spring 9. The high-pressure medium in the closed-loop emergency circuit pushes the front end face of the end cover sleeve 10 to the limit position of the steel ball lock at the end face of the hollow stepped hole in the piston head. The steel ball lock 4 rolls radially inward along the guide groove 5 and disengages from the upper locking groove 3, thus unlocking the steel ball lock in an emergency. The high-pressure medium pushes the piston rod 6, which drives the lead screw nut 7 to rotate in the opposite direction, and the piston rod 6 extends in an emergency. Under the condition of actuator power failure, the unlocking and piston rod extension tasks are completed.

[0016] The lead screw nut 7 is sealed by the end cover sleeve 10 on the end face of the fixed end stepped ring, which constrains the return spring 9 in the hollow stepped hole of the piston head and limits the degree of freedom of the steel ball lock 4 in the inner ring groove of the guide groove 5.

[0017] The upper locking groove 3 located on the inner wall of the outer cylinder 1 locks the steel ball lock 4 in the guide groove 5 of the piston head.

[0018] According to any of the above exemplary embodiments, when the piston rod 6 retracts to the bottom end, the steel ball lock 4 is located in the upper locking groove 3 and guide groove 5 on the inner surface of the outer cylinder 1, and the lower end rests against the outer ring surface of the end cover sleeve 10 to achieve locking.

[0019] When emergency unlocking and piston rod extension are required, high-pressure emergency medium enters the inner cavity of the outer cylinder 1 of the electromechanical actuator from the emergency energy inlet 2, pushing the end cover sleeve 10 to overcome the elastic force of the return spring 9 and disengage from the upper end of the steel ball lock 4. The steel ball lock 4 disengages from the upper locking groove 3, thereby realizing the piston rod 6 disengaging from the outer cylinder 1. At the same time, the high-pressure emergency medium pushes the piston rod 6 to extend, driving the lead screw nut 7 to reverse the rotation of the lead screw transmission pair 8.

[0020] For reference, in the description of the exemplary embodiment, the steel ball lock 4 is installed in the guide groove 5 of the piston rod 6, with its upper end installed in the upper locking groove 3 of the outer cylinder 1, which is equivalent in diameter to that of the steel ball lock 4, and its lower end resting against the outer annular surface of the end cover slide sleeve 10. The end cover slide sleeve 10 is pushed by the lead screw nut 7, together overcoming the elastic force of the return spring 9 to realize the locking or unlocking of the mechanical lock. When the steel ball lock 4 is located in the upper locking groove 3 of the outer cylinder 1, and its lower end rests against the outer annular surface of the end cover slide sleeve 10, the mechanical lock is locked.

[0021] When unlocking, the lead screw nut 7 drives the end cover sleeve 10 to disengage from the lower end of the ball lock. When emergency unlocking is required and the piston rod is extended, the clutch 12 disengages from the servo motor 11, and the high-pressure medium enters the electromechanical actuator from the emergency power inlet 2. The high-pressure medium pushes the end cover sleeve 10 to overcome the elastic force of the return spring 9 and disengage from the lower end of the ball lock 4, thus unlocking the mechanical lock. The high-pressure medium pushes the piston rod 6 to drive the lead screw nut 7, which in turn drives the lead screw 8 to rotate in the opposite direction, while the piston rod 6 extends.

[0022] The clutch can transmit the output torque of the motor to the output actuator through friction. When the drive servo motor fails, the clutch can separate the servo motor from the output actuator, thereby isolating the fault.

[0023] Although embodiments of the present invention have been shown and described above in detail, the description of the embodiments is only for the purpose of helping to understand the present invention; at the same time, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the content of this specification should not be construed as limiting the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An emergency unlocking electromechanical actuator, comprising: The gear transmission mechanism in the sealed cavity of the outer cylinder (1) of the electromechanical actuator is connected to the gear on the servo motor shaft, the lead screw transmission pair (8) meshing with the gear transmission mechanism is assembled in the transmission cavity of the outer cylinder (1), and the piston rod (6) that performs telescopic movement in the outer cylinder (1) and the lead screw nut (7) that is annularly sealed in the hollow stepped hole of the piston head are characterized in that: the servo motor (11) drives the lead screw gear to rotate through the gear transmission mechanism connected to the clutch (12) shaft, and the lead screw transmission pair (8) is connected to the sealing shaft. The hollow threaded raceway of the lead screw nut (7) passes through the piston rod (6) spacer ring and points to the bottom of the hollow cavity. The lead screw nut (7) is sealed by the end cover sleeve (10) on the end face of the fixed end stepped ring, which constrains the return spring (9) in the hollow stepped hole of the piston head. It is fitted on the lower end of the steel ball lock (4) which is evenly distributed around the circumference, and the upper locking groove (3) located on the inner wall of the outer cylinder (1) locks the steel ball lock (4) in the guide groove (5) of the piston head. During normal operation, the rotating lead screw transmission pair (8) drives the lead screw. Nut (7), through the step at the tail end of the screw nut (7), pushes the end cover sleeve (10) to overcome the elastic force of the return spring (9) and disengage from the lower end of the steel ball lock (4). The steel ball lock (4) rolls radially inward along the guide groove (5). After disengaging from the upper lock groove (3), the piston rod (6) extends out. During emergency operation, the clutch (12) disengages, and a high-pressure medium, which is different from electrical energy, enters the outer cylinder (1) cavity through the emergency energy inlet (2) on the outer ring surface of the outer cylinder (1), forming a force that pushes the end cover sleeve (10) to overcome the elastic force of the return spring (9). The closed-loop emergency circuit of the return spring (9) pushes the front end face of the end cover sleeve (10) to the limit position of the steel ball lock at the end face of the hollow stepped hole in the piston head. The steel ball lock (4) rolls radially inward along the guide groove (5) and disengages from the upper lock groove (3). The steel ball lock is unlocked in an emergency. The high-pressure medium pushes the piston rod (6) to drive the screw nut (7) to rotate the screw transmission pair (8) in the opposite direction. At the same time, the piston rod (6) extends in an emergency. Under the condition of power failure of the actuator, the unlocking and extension of the piston rod are completed.

2. The emergency unlocking electromechanical actuator as described in claim 1, characterized in that: The screw nut (7) is sealed by the end cover sleeve (10) ring on the end face of the fixed end step ring, which constrains the return spring (9) in the hollow step hole of the piston head and limits the degree of freedom of the steel ball lock (4) in the inner ring groove of the guide groove (5).

3. The emergency unlocking electromechanical actuator as described in claim 1, characterized in that: The upper locking groove (3) located on the inner wall of the outer cylinder (1) locks the steel ball lock (4) in the guide groove (5) of the piston head.

4. The emergency unlocking electromechanical actuator as described in claim 1, characterized in that: When the piston rod (6) retracts to the bottom, the steel ball lock (4) is located in the upper locking groove (3) and guide groove (5) on the inner surface of the outer cylinder (1), and the lower end rests against the outer ring surface of the end cover sleeve (10) to achieve locking.

5. The emergency unlocking electromechanical actuator as described in claim 1, characterized in that: When emergency unlocking and piston rod extension are required, high-pressure emergency medium enters the inner cavity of the outer cylinder (1) of the electromechanical actuator through the emergency energy inlet (2), pushing the end cover sleeve (10) to overcome the elastic force of the return spring (9) and disengage from the upper end of the steel ball lock (4). The steel ball lock (4) disengages from the upper locking groove (3), thereby realizing the piston rod (6) disengaging from the outer cylinder (1). At the same time, the high-pressure emergency medium pushes the piston rod (6) to extend, driving the screw nut (7) to reverse drive the screw transmission pair (8) to rotate.

6. The emergency unlocking electromechanical actuator as described in claim 1, characterized in that: The steel ball lock (4) is installed in the guide groove (5) of the piston rod (6), with its upper end installed in the upper locking groove (3) of the outer cylinder (1) with a diameter equivalent to that of the steel ball lock (4), and its lower end resting on the outer ring surface of the end cover sleeve (10).

7. The emergency unlocking electromechanical actuator as described in claim 6, characterized in that: The end cover sleeve (10) is pushed by the lead screw nut (7) and together overcomes the elastic force of the return spring (9) to realize the mechanical lock locking or unlocking. When the steel ball lock (4) is located in the upper locking groove (3) of the outer cylinder (1) and the lower end rests on the outer ring surface of the end cover sleeve (10), the mechanical lock is locked.

8. The emergency unlocking electromechanical actuator as described in claim 1, characterized in that: When unlocking, the screw nut (7) drives the end cover sleeve (10) to disengage from the lower end of the steel ball lock.

9. The emergency unlocking electromechanical actuator as described in claim 1, characterized in that: When emergency unlocking is required and the piston rod extends, the clutch (12) disengages from the servo motor (11), and the high-pressure medium enters the electromechanical actuator through the emergency energy inlet (2). The high-pressure medium pushes the end cover sleeve (10) to overcome the elastic force of the return spring (9) and disengage from the lower end of the steel ball lock (4), thereby unlocking the mechanical lock. The high-pressure medium pushes the piston rod (6) to drive the screw nut (7), which in turn drives the screw transmission pair (8) to rotate, and at the same time, the piston rod (6) extends.

10. The emergency unlocking electromechanical actuator as described in claim 1, characterized in that: The clutch can transmit the output torque of the motor to the output actuator through friction. When the drive servo motor fails, the clutch can separate the servo motor from the output actuator, thereby isolating the fault.

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