Compact emergency heavy-duty electric actuator
By introducing a radial emergency air inlet and a built-in mechanical lock into the electromechanical actuator, and using high-pressure medium to drive the unlocking of the piston rod cylinder, the problem of jamming due to reliance on electricity and transmission components in the prior art is solved, realizing emergency lowering without relying on electricity, and improving safety and reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY
- Filing Date
- 2022-12-25
- Publication Date
- 2026-06-12
AI Technical Summary
Existing heavy-duty landing gear retraction and deployment electromechanical actuators rely on electricity in emergency situations and cannot operate when transmission components are jammed, resulting in insufficient safety and failing to ensure the smooth deployment of the landing gear.
Design a compact emergency heavy-duty retractable electromechanical actuator, which adopts an outer cylinder with radial emergency air inlet and an internal mechanical lock structure. The piston rod cylinder is unlocked by high-pressure medium to achieve emergency lowering without relying on electricity. The locking mechanism of lead screw nut and retaining ring automatically unlocks when jammed or without power.
In the event of jamming or power failure of the transmission components, the piston rod cylinder can automatically extend in an emergency, improving the safety and reliability of the heavy-duty retraction and deployment electromechanical actuator and ensuring that the landing gear can be smoothly deployed in an emergency.
Smart Images
Figure CN115789010B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of servo actuators in aviation systems, specifically to an emergency release structure applied to heavy-duty retraction and deployment electromechanical actuators. More specifically, this invention relates to an innovative structure that improves the safety of heavy-duty retraction and deployment electromechanical actuators and enables the emergency release of the piston rod cylinder. Background Technology
[0002] With the continuous development of power fly-by-wire (PBW) technology for more-electric aircraft, power fly-by-wire actuators have been adopted in some advanced aircraft, increasingly replacing traditional hydraulic and pneumatic power transmission methods. A major development direction for power fly-by-wire actuators is the electromechanical actuator (EMA). The aircraft landing gear retraction and extension electromechanical actuator (EMA) is an electromechanical integrated electric retraction and extension device, consisting of a control circuit and a mechanical transmission execution part. The electric actuator cylinder of the mechanical transmission execution part, as a linear motion actuator, is an energy conversion device used to realize the linear reciprocating motion or less than 360° oscillating motion of the working mechanism. The control of the mechanical transmission part of the EMA realizes the control of the aircraft landing gear retraction and extension, including the landing gear retraction and extension process and its final positioning. The basic components of a common electric actuator cylinder are as follows: motor, gearbox, transmission components, ball screw pair, outer cylinder assembly, piston rod cylinder assembly, self-locking assembly, etc. An electromechanical actuator with a self-locking device prevents movement caused by external forces when it stops at a designated position. It is typically locked by a mechanical lock within the actuator. The most common type of mechanical lock is a ball lock, which consists of a ball, a locking groove, a conical piston, and a spring. In some applications with high safety requirements, the aircraft landing gear retraction electromechanical actuator (EMA) often also functions as a directional or lateral strut for the landing gear. This requires the landing gear to be securely locked in the lowered position and to withstand significant directional and lateral ground loads in that position. For example, EMAs used in aircraft landing gear retraction often do not use an internal mechanical lock for load bearing, but rather an external mechanical lock to bear heavy loads. Therefore, the actuator must have a certain safety margin to ensure the landing gear can still be lowered smoothly in emergency situations. The landing gear is a crucial component of an aircraft, and the actuator plays a vital role in its structure. Among the various working components of modern aircraft landing gear systems, the retraction mechanism has a relatively high probability of failure during use. In hydraulic actuators, the piston rod can extend from the outer cylinder by unloading hydraulic pressure during emergency landing gear deployment. In contrast, in electric actuators, the piston rod can only rotate the lead screw to pull the piston out. This method consumes more energy under heavy loads and cannot ensure the landing gear locks smoothly in the deployed position; it may even jam during deployment. Therefore, it cannot meet the high reliability requirements of aircraft. Currently, electromechanical actuators are widely used in electric folding systems, electric winch systems, landing gear servo systems, servo control systems, electric retraction and deployment systems, and intelligent robots. The retraction and deployment electromechanical actuator (EMA) control system controls the aircraft landing gear retraction and deployment by controlling the mechanical transmission of the landing gear EMA, including the landing gear retraction and deployment process, positioning detection, and locking the landing gear in the retracted and deployed positions. Typically, the retraction and deployment electromechanical actuator (EMA) control system needs to control multiple landing gears simultaneously (e.g., one nose landing gear and two main landing gears).The landing gear system is the only component that supports the entire weight of the aircraft, and its proper deployment and retraction directly affect flight safety. Typical aircraft landing gear systems employ a dual-redundancy design. Conventional dual-redundant electromechanical actuators still rely on electricity for emergency deployment, and they cannot function when transmission components such as lead screws, gears, and reducers become jammed. Currently, commonly used multi-redundant designs for electromechanical actuators involve a backup motor; when the main motor fails, the backup motor operates to achieve emergency deployment or retraction of the piston rod. However, this structure cannot solve the problem of emergency deployment or retraction when lead screws, gears, and reducers become jammed. Summary of the Invention
[0003] The purpose of this invention is to address the shortcomings of existing technologies and solve the problem of insufficient safety of single-redundant conventional heavy-duty retraction electromechanical actuators. It provides a simple structural solution that enables emergency lowering of the piston rod cylinder without relying on electricity. This effectively solves the problem that conventional dual-redundant electromechanical actuators still require electricity for emergency lowering, and cannot function when transmission components such as lead screws, gears, and reducers are jammed. This invention achieves multi-redundant emergency response for different working media.
[0004] The technical solution adopted by this invention to solve its technical problem is: a compact emergency heavy-duty retractable electromechanical actuator, comprising: an outer cylinder 2 with a radial emergency air inlet 1, a piston cylinder 3 reciprocating within the cavity of the outer cylinder 2, and a transmission gear connected to a lead screw 6 via a servo motor spindle. The characteristic feature is that: a rolling bearing nut 8 is fitted to the lead screw 6 via a bearing seat at the tail of the outer cylinder 2, and a lip locking ring 10 at the end of the lead screw nut 8 facing the cylinder lip is constrained to the end face of the stepped cylinder on the inner wall of the piston cylinder 3. The lip locking ring 10 locks a retaining ring 7 mounted on the stepped cylinder at the tail of the piston cylinder 3 onto the end face of the flanged ring of the sealing sleeve that passes through the follower piston 4. The piston cylinder 3 seals the follower piston 4, and a spring 5 is constrained within the spacer ring between the sleeve and the hollow cavity of the piston cylinder 3. At the bottom, the piston rod cylinder 3 is equipped with a built-in mechanical lock that can be unlocked by emergency medium entering the high-pressure chamber of the outer cylinder 2 through the air inlet 1. The lead screw 6 extends into the blind end chamber of the piston rod cylinder 3 and bears the external heavy load together with the piston cylinder 3. When the transmission component is jammed or loses power and the piston rod cylinder 3 needs to be extended in an emergency, the emergency high-pressure medium enters the motion chamber at the tail of the actuator from the air inlet 1 of the outer cylinder 2, pushing the follower piston rod cylinder 3 to extend out of the outer cylinder 2. The lead screw nut 8 drives the piston rod cylinder 3 to overcome the elastic force of the spring 5 and disengage from the inner ring of the retaining ring 7. The piston rod cylinder 3 pushes the retaining ring 7 to slide out along the lip locking ring 10 of the lead screw nut 8, realizing the unlocking between the follower piston 4 and the lead screw nut 8. The lead screw nut 8 is separated from the piston rod cylinder 3. The lead screw nut 8 drives the piston rod cylinder 3 to overcome the heavy load and extend the piston rod cylinder 3 in an emergency.
[0005] Compared with the prior art, the present invention has the following advantages:
[0006] This invention employs an outer cylinder 2 with a radial emergency air inlet 1, and a piston cylinder 3 reciprocating within the cavity of the outer cylinder 2. A servo motor spindle is connected to a lead screw 6 via a transmission gear, which holds a retaining ring 7 within the locking groove 9 of the lead screw nut 8. The resulting emergency heavy-duty retraction electromechanical actuator has a simple structure and enables emergency lowering of the piston cylinder without relying on electricity. This improves the safety of the heavy-duty retraction electromechanical actuator.
[0007] This invention designs a locking mechanism between the piston rod cylinder 3 and the lead screw nut 8, which can be driven by an emergency medium introduced through the air inlet 1 to unlock and release. When the heavy-duty retractable electromechanical actuator is operating normally, this mechanism is in a locked state. When the lead screw nut 8 drives the piston rod cylinder 3 to overcome heavy loads, and an emergency operation is required, the emergency medium entering the actuator can push the follower piston rod cylinder 3 out of the outer cylinder 2. The lead screw nut 8 drives the piston rod cylinder 3 to disengage from the inner ring of the retaining ring 7, and the piston rod cylinder 3 pushes the retaining ring 7 out of the locking groove 9 of the lead screw nut 8. This unlocks the follower piston 4 and the lead screw nut 8, and pushes out the piston rod cylinder 3, enabling the emergency lowering of the piston rod cylinder. This solves the problem of insufficient safety due to the single-redundancy design of conventional heavy-duty retractable electromechanical actuators.
[0008] This invention is applicable to emergency operating schemes for non-similar energy sources in heavy-duty retraction and deployment electromechanical actuators. Attached Figure Description
[0009] Figure 1 This is a schematic diagram of the structure of a compact emergency heavy-duty retractable electromechanical actuator in normal working condition.
[0010] Appendix Figure 2 yes Figure 1 A partially enlarged schematic diagram of the locking mechanism that drives unlocking and disengagement under normal operating conditions, showing the cross-section of the mechanism.
[0011] In the diagram: 1. Air inlet, 2. Outer cylinder, 3. Piston rod cylinder, 4. Follower piston, 5. Spring, 6. Lead screw, 7. Snap ring, 8. Lead screw nut, 9. Lock groove, 10. Lip lock ring, 11. Upper lock surface.
[0012] 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
[0013] See Figure 1 , Figure 2In the preferred embodiment described below, a compact emergency heavy-duty retractable electromechanical actuator includes: an outer cylinder 2 with a radial emergency air inlet 1; a piston cylinder 3 reciprocating within the cavity of the outer cylinder 2; a transmission gear connected to a lead screw 6 via a servo motor spindle; a lead screw nut 8 fitted to a rolling bearing fixed to the tail bearing seat of the outer cylinder 2; a lip locking ring 10 constraining the end of the lead screw nut 8 towards the cylinder lip to the end face of the stepped cylinder on the inner wall of the piston cylinder 3; the lip locking ring 10 locking a retaining ring 7 mounted on the stepped cylinder at the tail of the piston cylinder 3 to the end face of the flanged ring of the sealing sleeve of the follower piston 4; the piston cylinder 3 sealing the follower piston 4; and a spring 5 constraining the bottom end of the spacer ring in the hollow cavity of the sleeve and the piston cylinder 3, forming a retractable... The piston rod cylinder 3 has an internal mechanical lock that can be unlocked by emergency medium entering the high-pressure chamber of the outer cylinder 2 through the air inlet 1. The lead screw 6 extends into the blind end chamber of the piston rod cylinder 3 and bears the external heavy load together with the piston cylinder 3. When the transmission component is jammed or loses power and the piston rod cylinder 3 needs to be extended in an emergency, the emergency high-pressure medium enters the motion chamber at the tail of the actuator from the air inlet 1 of the outer cylinder 2, pushing the follower piston rod cylinder 3 to extend out of the outer cylinder 2. The lead screw nut 8 drives the piston rod cylinder 3 to overcome the elastic force of the spring 5 and disengage from the inner ring of the retaining ring 7. The piston rod cylinder 3 pushes the retaining ring 7 to slide out along the lip locking ring 10 of the lead screw nut 8, realizing the unlocking between the follower piston 4 and the lead screw nut 8. The lead screw nut 8 is separated from the piston rod cylinder 3. The lead screw nut 8 drives the piston rod cylinder 3 to overcome the heavy load and extend the piston rod cylinder 3 in an emergency.
[0014] The follower piston 4 is sealed on the hollow inner wall cavity of the piston rod cylinder 3, and is coupled to the spring 5 through the inner ring sealing the rigid body end face.
[0015] The lead screw nut 8 holds the retaining ring 7 on the outer ring surface of the follower piston 4 through the locking groove 9.
[0016] When the electromechanical actuator is working normally, the lead screw 6 rotates, and the lead screw nut 8 pushes the piston rod cylinder 3 to move. When the lead screw 6 rotates in the opposite direction, the lip locking ring 10 of the lead screw nut 8 and the upper locking surface 11 of the retaining ring 7 are engaged at a chamfer, causing the retaining ring 7 to push the piston rod cylinder 3 back. Because the lead screw nut 8 pushes the piston rod cylinder 3 in surface contact, and the lead screw nut 8 pushes the retaining ring 7, which in turn pushes the piston rod cylinder 3 in surface contact, the electromechanical actuator can withstand heavy loads during retraction and extension.
[0017] 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. A compact emergency heavy-duty retractable electromechanical actuator, comprising: An outer cylinder (2) with a radial emergency air inlet (1) is fitted with a piston rod cylinder (3) that reciprocates within the cavity of the outer cylinder (2). A transmission gear is connected to the lead screw (6) via a servo motor spindle. The characteristic feature is that the lead screw (6) is fitted with a lead screw nut (8) via a rolling bearing fixed to the bearing seat at the tail of the outer cylinder (2). A lip locking ring (10) at the end of the lead screw nut (8) facing the cylinder lip is constrained to the end face of the stepped cylinder on the inner wall of the piston rod cylinder (3). The lip locking ring (10) will be fitted to the piston rod cylinder (3). 3) The retaining ring (7) on the tail stepped cylinder is locked on the end face of the flange ring of the ring sealing sleeve of the piston rod cylinder (4). The piston rod cylinder (3) ring seals the piston rod cylinder (4), and the spring (5) is constrained at the bottom end of the spacer ring in the hollow cavity of the sleeve and the piston rod cylinder (3). This forms a built-in mechanical lock that can be unlocked by the emergency medium driving the piston rod cylinder (3) to enter the outer cylinder (2) high pressure cavity through the air inlet (1). The screw (6) extends into the blind end cavity of the piston rod cylinder (3) and together with the piston rod cylinder (3), it bears the heavy load from the outside. When the transmission components are jammed or lose power and the piston rod cylinder (3) needs to be extended in an emergency, the emergency high-pressure medium enters the motion chamber at the tail of the actuator from the air inlet (1) of the outer cylinder (2), pushing the follower piston rod cylinder (3) to extend out of the outer cylinder (2). The screw nut (8) drives the piston rod cylinder (3) to overcome the elastic force of the spring (5) and disengage from the inner ring of the retaining ring (7). The lip locking ring (10) slides out from the lip of the retaining ring (7) to the stepped cylinder end face of the piston rod cylinder (3), realizing the unlocking between the follower piston (4) and the screw nut (8). The screw nut (8) disengages from the piston rod cylinder (3), and the screw nut (8) drives the piston rod cylinder (3) to overcome the heavy load movement and extend the piston rod cylinder (3) in an emergency.
2. The compact emergency heavy-duty retractable electromechanical actuator as described in claim 1, characterized in that: The follower piston (4) is sealed on the hollow inner wall cavity of the piston rod cylinder (3) and is coupled to the spring (5) through the inner ring sealing the rigid body end face.
3. The compact emergency heavy-duty retractable electromechanical actuator as described in claim 1, characterized in that: When the electromechanical actuator is working normally, the lead screw (6) rotates and the lead screw nut (8) pushes the piston rod cylinder (3) to move. When the lead screw (6) rotates in the opposite direction, the lip locking ring (10) of the lead screw nut (8) and the upper locking surface (11) of the retaining ring (7) are cut and fit together, which drives the retaining ring (7) to push the piston rod cylinder (3) to retract.
4. The compact emergency heavy-duty retractable electromechanical actuator as described in claim 1, characterized in that: The lead screw nut (8) pushes the piston rod cylinder (3) contact surface, and the lead screw nut (8) pushes the retaining ring (7) and then pushes the piston rod cylinder (3), so that the electromechanical actuator can bear heavy loads for retraction and extension.
5. The compact emergency heavy-duty retractable electromechanical actuator as described in claim 1, characterized in that: The lead screw nut (8) holds the retaining ring (7) on the outer ring surface of the follower piston (4) through the locking groove (9).