Centralized all-electric dual-redundant emergency discharge actuator

Abstract

This invention proposes a centralized, fully electric, dual-redundant emergency discharge electromechanical actuator, which is stable, safe, reliable, and has smooth speed regulation. The invention provides the following technical solution: the main motor and auxiliary motor can operate simultaneously, or either motor can operate while the other is a cold backup. When the main and auxiliary motors operate simultaneously, the main lead screw cylinder drives the main lead screw nut and auxiliary lead screw to extend, and the auxiliary lead screw drives the auxiliary lead screw nut and the fitted piston cylinder to extend. If the main motor is operating and the auxiliary motor fails, the main motor drives the main lead screw cylinder to rotate via the main transmission gear, driving the main lead screw nut to push the auxiliary lead screw nut and the fitted piston cylinder to extend over the load. If the main motor fails or the transmission chain is jammed, the auxiliary motor operates, driving the transmission shaft to rotate via the auxiliary transmission gear. The transmission shaft drives the auxiliary lead screw, which meshes with the auxiliary lead screw, to rotate synchronously, driving the auxiliary lead screw nut and the fitted piston cylinder to extend over the load. This invention effectively solves the problem of low reliability in conventional dual-redundant electromechanical actuators.

Description

Technical Field

[0001] This invention relates to a dual-redundant emergency release structure applied to all-electric actuators. More specifically, this invention relates to an innovative structure that improves the safety and reliability of all-electric actuators, enabling the other motor and transmission components to extend the piston cylinder in the event of failure of one motor or jamming of the transmission chain. Background Technology

[0002] An actuator is a transmission mechanism in a motion control device that performs maneuvering actions. Early actuator systems, from mechanical transmission to later hydraulic transmission, all utilized centralized hydraulic power sources in aircraft. Recently developed all-electric hydraulic servo systems account for a significant portion of the system weight. These hydraulic servo mechanisms suffer from drawbacks such as complex structure, high failure rate, large power transmission loss, and high heat load, hindering system integration and reducing reliability. With the emergence of the concept of all-electric transmission systems, electromechanical actuators, as linear motion execution elements, are energy conversion devices used to achieve linear reciprocating motion or oscillating motion less than 360° in working mechanisms. The basic components of a common electromechanical actuator are as follows: motor, gearbox, transmission components, ball screw pair, outer cylinder assembly, piston cylinder assembly, self-locking assembly, etc. Electromechanical actuators with self-locking devices prevent lateral movement caused by external forces when stopped at a defined position. This is typically achieved by a splined sleeve on the actuator cylinder and a mechanical lock. The most common type of mechanical lock is a ball lock, which consists of a steel ball, a locking groove, a conical piston, and a spring.

[0003] In applications with high safety and mission reliability requirements, such as electromechanical actuators used in aircraft landing gear retraction and extension, a safety margin for landing gear deployment is essential. Therefore, electromechanical actuators (EMAs) are critical components of flight control systems, and their reliability directly impacts flight safety. To improve reliability, EMAs primarily utilize redundancy technology, employing redundant system design. The main method for increasing system power density is using high-power-density motors for transmission. In a redundant EMA, after a local control channel failure, both channels operate simultaneously in active / active mode, jointly driving the tandem hydraulic cylinder, leading to force conflict. There are five solutions to this force conflict: ① Strictly control servo loop parameters, especially feedback gain tolerance, improve component machining accuracy, minimize channel errors, and enhance channel consistency. Since various types of system errors are unavoidable, this only alleviates force conflict to a certain extent and increases cost. ② Eliminate or reduce input signal differences by voting on single-value command signals, but cannot avoid other errors. ③ Eliminate or reduce output signal differences by voting on displacement feedback signals and adopting a waiting stepping method. The nonlinearity of the waiting step method reduces the natural frequency of the actuation system. ④ Reducing the pressure gain and increasing damping can decrease the amplitude of force conflict, but this reduces the system's stiffness and dynamic performance. ⑤ Using equalization techniques forces the output forces of each channel to become more consistent, thereby alleviating or eliminating force conflict. Of the five methods mentioned above, equalization techniques are the best for reducing force conflict. Of the five methods currently used to reduce force conflict, the other four can only reduce it to a certain extent and have some negative impact on the system. The presence of force conflict reduces the system's response speed and affects its positional accuracy.

[0004] To improve the reliability of the system's remaining control channels in completing flight missions and increase the system's power density, two operating modes for the remaining subsystems are active parallel operation and standby switching operation. The latter refers to one or more subsystems operating while the others are in standby mode. When a working subsystem fails, the monitoring device detects the fault and switches to the working standby subsystem, allowing the system to continue operating. To avoid power conflicts during simultaneous operation, redundant electromechanical actuators are generally designed with a backup motor. When the main motor fails, the backup motor operates to achieve emergency piston cylinder lowering. However, this cannot solve the single-point failure of the lead screw pair jamming, resulting in low mission reliability and poor practicality.

[0005] Traditional redundant electromechanical actuators mostly employ differentials or fault-tolerant motors. The drawback of using differentials is the increased rotational inertia, torque, and weight, thus limiting their application to smaller, more frequently used actuators. To address the current contention issue in the electromagnetic system of electromechanical actuators, a dual-redundant electromechanical actuator is developed. This actuator uses a permanent magnet brushless DC motor as its core, employing a balanced control method for the dual-redundant winding current of the brushless DC motor. The motor in this dual-redundant electromechanical actuator system is a dual-redundant torque-magnetically coupled samarium cobalt permanent magnet brushless DC motor, with two identical three-phase windings on the stator. The two windings are electrically 60 degrees out of phase. Two photoelectric position sensors are located on the rotor, forming a dual-redundant dual-trigger sensor system. The outputs of each power converter, through magnetic coupling, apply the combined torque to the motor's main shaft to drive the aircraft's control surfaces. The dual-redundant controller consists of two microcontrollers and peripheral circuitry, employing a backup principle: one operates actively, while the other operates as a hot backup. Based on system control commands and status information, two PWM wave signals are issued to control the two power converters. Balanced regulation is necessary to ensure the current balance between the two motor windings. However, balancing techniques can mask true system faults; therefore, appropriate fault thresholds must be set to prevent faults from being concealed by current balancing. Due to the imperfect symmetry between the two channels in a dual-redundant system and the influence of various factors such as power supply differences, load variations, and ambient temperature changes, current imbalances in the two motor windings can occur. Therefore, a "current contention" phenomenon exists during the operation of a dual-redundant electromechanical actuator system. Simulations of parallel operation demonstrate that when the voltage difference between the two power converters increases, severe current imbalances occur, even leading to a situation where one winding is in a motoring state while the other is in a generating state, causing severe motor overheating and endangering system safety. In reality, many other factors can also cause inconsistent output displacements between the two channels. For example, differences in manufacturing processes, energy sources, components such as sensors, controllers, environmental changes (temperature), wear (performance degradation over long-term use), and changes in the dynamic hydraulic stiffness of actuators can all lead to differences in output displacement and speed. Summary of the Invention

[0006] In view of the above-mentioned problems of the prior art, the purpose of this invention is to provide a solution that is simple in structure, stable in operation, safe and reliable, with smooth speed regulation, and capable of extending the piston cylinder in an emergency when only electrical energy is available. This effectively solves the problem of single-point failure of the lead screw pair jamming, which cannot be addressed by conventional dual-redundant electromechanical actuators, and achieves all-electric redundancy emergency response.

[0007] The technical solution adopted by this invention to solve its technical problem is: a centralized all-electric dual-redundant emergency discharge electro-actuator, comprising: a main motor 1 mounted on the upper end of the outer cylinder 3 as the main power source and an auxiliary motor 11 mounted on the lower end as the emergency power source; the main motor 1 and the auxiliary motor 11, as backup power output sources, are respectively equipped with transmission gear pairs meshing with the main lead screw cylinder 4 and the transmission shaft 13; and a main lead screw nut 6 fitted on the outer helical raceway of the main lead screw cylinder 4. The main motor 1's main shaft meshes with the main lead screw cylinder 4 gear in the transmission cavity through the main transmission gear 2, and the auxiliary motor 11's main shaft gear meshes with the outer end gear of the transmission shaft 13 in the transmission cavity through the auxiliary transmission gear 12. The gears mesh, the outer spline of the right end of the drive shaft 13 engages with the auxiliary lead screw 8, and the truncated spline of the piston at the end of the shaft extending from the port of the main lead screw cylinder 4 meshes with the spline groove of the inner cavity of the auxiliary lead screw 8, which is equipped with a bearing through the receiving cavity of the main lead screw nut 6. This forms two relatively independent transmission chains: the main lead screw cylinder 4 can be driven by the main motor 1, and the auxiliary lead screw 8 can be driven by the auxiliary motor 11. Both are integrated together by the piston cylinder 10 with the auxiliary lead screw nut 9 inside. This forms a dual-redundant emergency release control mechanism in which the main lead screw cylinder 4 and the drive shaft 13 mesh with the gears of the main and auxiliary motors in an alternating and parallel manner to transmit loads. If either motor fails or its corresponding transmission chain jams, the other motor independently completes the task of extending the piston cylinder.

[0008] Compared with the prior art, the present invention has the following advantages: This invention employs a main motor 1 mounted on the upper side of the outer cylinder 3 as the main power source and an auxiliary motor 11 mounted on the lower side as an emergency power source. As backup power output sources, the main motor 1 and the auxiliary motor 11 are equipped with transmission gear pairs meshing with the main lead screw cylinder 4 and the transmission shaft 13, and a main lead screw nut 6 fitted on the outer helical raceway of the main lead screw cylinder 4. The structure is simple, the operation is stable, safe and reliable, and the speed regulation is smooth. It can enable the piston cylinder to extend in an emergency when only electrical energy is available.

[0009] This invention employs a main motor 1 whose main shaft meshes with the main lead screw cylinder 4 gear in the transmission cavity via the main transmission gear 2. The auxiliary motor 11's main shaft gear meshes with the outer end gear of the transmission shaft 13 via the auxiliary transmission gear 12 and the splined sleeve of the main lead screw cylinder 4 in the transmission cavity. The outer splined teeth of the transmission shaft 13 mesh with the splined groove of the inner cavity of the auxiliary lead screw 8. When either motor fails or its corresponding transmission chain jams, the other motor can independently complete the task of extending the piston cylinder. This improves the safety and reliability of the all-electric actuator. Even when one motor fails or the transmission chain jams, the other motor and transmission components can complete the piston cylinder extension action, thus solving the problem of single-point failure due to lead screw jamming that conventional electromechanical actuators cannot address.

[0010] This invention axially mounts a load-bearing, freely rotating auxiliary lead screw 8 onto the main lead screw nut 6, allowing the main lead screw cylinder 4 to be driven by the main motor 1 and the auxiliary lead screw 8 to be driven by the auxiliary motor 11, forming two relatively independent transmission chains, which are integrated together by the piston cylinder 10. When the main motor 1 and the auxiliary motor 11 work simultaneously, the piston cylinder extension speed is twice that of a single motor, increasing actuator power, accelerating system response speed, and significantly reducing force conflict, both in amplitude and duration. Simulation verification shows a significant reduction in the amplitude of force conflict and a shortened time for force conflict to disappear. The dual-redundant emergency release control mechanism, with staggered parallel meshing of lead screw gears, allows the main motor 1 and auxiliary motor 11 to work simultaneously, accelerating the time to reach equilibrium. By shortening the time to reach equilibrium, it better meets the requirements of rapid, high-power, and redundant operation of aircraft landing gear systems. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the piston cylinder retracted state of the centralized, fully electric, dual-redundant emergency discharge actuator.

[0012] Figure 2 This is a schematic diagram of the meshing of the drive shaft and the auxiliary lead screw spline of the centralized all-electric dual-redundant emergency discharge electromechanical actuator.

[0013] In the diagram: 1. Main motor, 2. Main transmission gear, 3. Outer cylinder, 4. Main lead screw cylinder, 5. Thrust angular contact ball bearing, 6. Main lead screw nut, 7. Double-direction thrust angular contact ball bearing, 8. Secondary lead screw, 9. Secondary nut, 10. Piston cylinder, 11. Secondary motor, 12. Secondary transmission gear, 13. Transmission shaft.

[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] See Figure 1In the preferred embodiment described below, a centralized all-electric dual-redundant emergency discharge actuator includes: a main motor 1 mounted on the upper end of the outer cylinder 3 as the main power source and an auxiliary motor 11 mounted on the lower end as the emergency power source; the main motor 1 and the auxiliary motor 11, as backup power output sources, are respectively equipped with transmission gear pairs meshing with the main lead screw cylinder 4 and the transmission shaft 13; and a main lead screw nut 6 fitted on the outer helical raceway of the main lead screw cylinder 4. The main motor 1's main shaft meshes with the gear of the main lead screw cylinder 4 in the transmission cavity through the main transmission gear 2, and the auxiliary motor 11's main shaft gear meshes with the outer end gear of the transmission shaft 13 in the transmission cavity through the auxiliary transmission gear 12. The transmission shaft 13 is connected to the auxiliary lead screw 8 via an external spline on its right end. The piston frustum spline at the end of the shaft extending from the main lead screw cylinder 4 engages with the spline groove of the inner cavity of the auxiliary lead screw 8, which is fitted with a bearing through the cavity of the main lead screw nut 6. This forms two relatively independent transmission chains: the main lead screw cylinder 4 can be driven by the main motor 1, and the auxiliary lead screw 8 can be driven by the auxiliary motor 11. Both chains are integrated together by the piston cylinder 10 with the auxiliary lead screw nut 9 inside. This creates a dual-redundant emergency control mechanism where the main lead screw cylinder 4 and the transmission shaft 13 alternately and in parallel mesh with the gears of the main and auxiliary motors to rotate and transmit loads. If either motor fails or its corresponding transmission chain jams, the other motor independently completes the task of extending the piston cylinder.

[0016] As backup power sources, the main motor 1 and the auxiliary motor 11 can work simultaneously or either one of them can work while the other motor is a cold backup.

[0017] The main motor 1 and the auxiliary motor 11 work simultaneously. The main lead screw cylinder 4, which outputs the speed of the main motor 1, drives the main lead screw nut 6. The auxiliary motor 11 drives the auxiliary lead screw nut 9 on the outer helical raceway of the auxiliary lead screw 8, and the piston cylinder 10, which moves in extension and retraction in the outer cylinder 3, to move together. The auxiliary lead screw nut 9, which is installed in the hollow stepped hole in the piston cylinder 10, transmits the piston cylinder load sequentially to the auxiliary lead screw 8 and the main lead screw nut 6, and then to the main lead screw cylinder 4 through the thrust angular contact ball bearing 5. The main lead screw cylinder 4 drives the main lead screw nut 6 and the auxiliary lead screw 8 to extend, and the auxiliary lead screw 8 drives the auxiliary lead screw nut 9 and the fitted piston cylinder 10 to extend. If the main motor 1 fails or the transmission chain is jammed, the auxiliary motor 11 works. The auxiliary motor 11 drives the transmission shaft 13 to rotate through the auxiliary transmission gear 12. The transmission shaft 13 drives the auxiliary lead screw 8, which meshes with it through the spline, to rotate synchronously, driving the auxiliary lead screw nut 9 and the fitted piston cylinder 10 to extend over the load.

[0018] The main screw cylinder 4 is screwed to the main screw nut 6 via the thrust angular contact ball bearing 5 on the bearing seat in the transmission cavity of the outer cylinder 3. The main screw nut 6 is driven to move together by the double-arm thrust angular contact ball bearing 7 constrained by the double-arm bearing seat assembled in the hollow stepped hole inside the main screw nut 6, the auxiliary screw nut 9 fitted on the outer helical raceway of the auxiliary screw 8, and the piston cylinder 10 that moves in telescopic motion in the outer cylinder 3.

[0019] The inner ring of the thrust angular contact ball bearing 5, installed in the hollow stepped hole of the outer cylinder 3, is axially limited on the upper stepped shaft of the main screw cylinder 4 and bears the load of the main screw cylinder 4; the inner ring of the bidirectional thrust angular contact ball bearing 7, installed in the hollow stepped hole of the main screw nut 6, is axially limited on the upper stepped shaft of the auxiliary screw 8 and bears the load of the auxiliary screw 8. During normal operation, the main motor 1 and the auxiliary motor 11 can work simultaneously or either motor can work while the other motor is in cold standby. When the main motor 1 and the auxiliary motor 11 work simultaneously, the main lead screw cylinder 4 drives the main lead screw nut 6 and the auxiliary lead screw 8 to extend, and the auxiliary lead screw 8 drives the auxiliary lead screw nut 9 and the set piston cylinder 10 to extend.

[0020] 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 centralized, fully electric, dual-redundant emergency discharge actuator, comprising: The main motor (1) mounted on the upper side of the outer cylinder (3) as the main power source and the auxiliary motor (11) mounted on the lower side as the emergency power source, as backup power output sources, the main motor (1) and the auxiliary motor (11) are respectively equipped with transmission gear pairs meshing with the main screw cylinder (4) and the transmission shaft (13), and the main screw nut (6) is fitted on the outer spiral raceway of the main screw cylinder (4). The main motor (1) main shaft meshes with the main screw cylinder (4) gear in the transmission cavity through the main transmission gear (2), the auxiliary motor (11) main shaft gear meshes with the outer end gear of the transmission shaft (13) in the transmission cavity through the auxiliary transmission gear (12), and the right end of the transmission shaft (13) has an outer spline sleeve. The auxiliary lead screw (8) is engaged, and the truncated cone spline of the piston at the end of the shaft extending from the port of the main lead screw cylinder (4) meshes with the spline groove of the inner cavity of the auxiliary lead screw (8) which is equipped with a bearing through the cavity of the main lead screw nut (6). This forms two relatively independent transmission chains: the main lead screw cylinder (4) can be driven by the main motor (1), and the auxiliary lead screw (8) can be driven by the auxiliary motor (11). The piston cylinder (10) with the inner sleeve of the auxiliary lead screw nut (9) is integrated together. This forms a dual-redundant emergency release control mechanism in which the main lead screw cylinder (4) and the transmission shaft (13) mesh with the gears of the main and auxiliary motors in an alternating and parallel manner to transmit load. If either motor fails or its corresponding transmission chain is jammed, the other motor independently completes the task of extending the piston cylinder.

2. The centralized all-electric dual-redundant emergency discharge actuator as described in claim 1, characterized in that: The main motor (1) and the auxiliary motor (11), which serve as backups for each other, can work simultaneously or either motor can work while the other motor is a cold backup.

3. The centralized all-electric dual-redundant emergency discharge actuator as described in claim 1, characterized in that: The main motor (1) and the auxiliary motor (11) work simultaneously. The main screw cylinder (4), which outputs the speed of the main motor (1), drives the main screw nut (6). The auxiliary motor (11) drives the auxiliary screw nut (9) on the outer spiral raceway of the auxiliary screw (8) and the piston cylinder (10) that moves in the outer cylinder (3) together. The auxiliary screw nut (9) installed in the hollow stepped hole in the piston cylinder (10) transmits the piston cylinder load to the auxiliary screw (8) and the main screw nut (6) in sequence. The load is then transmitted to the main screw cylinder (4) through the thrust angular contact ball bearing (5). The main screw cylinder (4) drives the main screw nut (6) and the auxiliary screw (8) to extend. The auxiliary screw (8) drives the auxiliary screw nut (9) and the fitted piston cylinder (10) to extend.

4. The centralized all-electric dual-redundant emergency discharge actuator as described in claim 3, characterized in that: If the main motor (1) fails or the transmission chain is jammed, the auxiliary motor (11) will work. The auxiliary motor (11) will drive the transmission shaft (13) to rotate through the auxiliary transmission gear (12). The transmission shaft (13) will drive the auxiliary lead screw (8) that meshes with it to rotate synchronously, driving the auxiliary lead screw nut (9) and the piston cylinder (10) to extend over the load.

5. The centralized all-electric dual-redundant emergency discharge actuator as described in claim 1, characterized in that: The main screw cylinder (4) is screwed to the main screw nut (6) through the thrust angular contact ball bearing (5) on the bearing seat in the transmission cavity of the outer cylinder (3). The main screw nut (6) is driven to move together by the double thrust angular contact ball bearing (7) constrained by the double-arm bearing seat assembled in the hollow stepped hole of the main screw nut (6), the auxiliary screw nut (9) fitted on the outer helical raceway of the auxiliary screw (8), and the piston cylinder (10) that makes telescopic movements in the outer cylinder (3).

6. The centralized all-electric dual-redundant emergency discharge actuator as described in claim 1, characterized in that: The inner ring of the thrust angular contact ball bearing (5), which is installed in the hollow stepped hole of the outer cylinder (3), is axially limited on the upper stepped shaft of the main screw cylinder (4) and bears the load of the main screw cylinder (4).

7. The centralized all-electric dual-redundant emergency discharge actuator as described in claim 1, characterized in that: The inner ring of the bidirectional thrust angular contact ball bearing (7), which is installed in the hollow stepped hole of the main screw nut (6), is axially limited on the upper stepped shaft of the auxiliary screw (8) and bears the load of the auxiliary screw (8).

8. The centralized all-electric dual-redundant emergency discharge actuator as described in claim 1, characterized in that: During normal operation, the main motor (1) and the auxiliary motor (11) can work simultaneously or either motor can work while the other motor is in cold standby. When the main motor (1) and the auxiliary motor (11) work simultaneously, the main screw cylinder (4) drives the main screw nut (6) and the auxiliary screw (8) to extend, and the auxiliary screw (8) drives the auxiliary screw nut (9) and the fitted piston cylinder (10) to extend.

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