CN219802072U

CN219802072U - Multi-stage step actuating motor electric actuator

Info

Publication number: CN219802072U
Application number: CN202223467470.8U
Authority: CN
Inventors: 郭智; 匡克焕; 汪驰; 詹翔
Original assignee: SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY CO Ltd
Current assignee: SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY CO Ltd
Priority date: 2022-12-25
Filing date: 2022-12-25
Publication date: 2023-10-03
Anticipated expiration: 2032-12-25

Abstract

The multi-stage step actuating motor electric actuator provided by the utility model has the advantages of good step actuating controllability and high control precision. The method is realized by the following technical scheme: the main screw barrel drives an auxiliary screw rod, the front stepped hole bearing accommodating cavity of which is restrained by the rear end surface of the bidirectional thrust bearing and the auxiliary screw nut, through a main screw nut restrained by the bottom of the primary piston rod, and the auxiliary screw rod axially linearly stretches and contracts in the secondary piston rod moving cavity; the secondary servo motor drives the auxiliary screw rod sleeved by the spline to do rotary motion together through the transmission shaft, the auxiliary screw rod nut is driven to do axial motion, in the step motion, the main screw rod cylinder can be driven by the primary servo motor through the main screw rod nut, the auxiliary screw rod can be driven by the secondary servo motor to rotate through the auxiliary screw rod nut, two transmission chains are respectively formed, the primary piston rod is driven to do linear telescopic motion in the cylinder barrel motion cavity, and the secondary piston rod is driven to do at least two transmission chain free rotation channels of the step motion of telescopic motion in the primary piston rod motion cavity.

Description

Multi-stage step actuating motor electric actuator

Technical Field

The utility model belongs to the technical field of electromechanical actuators, and relates to a long-stroke retractable structure applied to an electromechanical actuator, in particular to an innovative structure which can greatly reduce the structural length of the electromechanical actuator under a specified stroke or greatly increase the working stroke under the specified structural length.

Background

At present, most civil aircraft hydraulic systems adopt a centralized oil source, and an engine drives a pump to provide hydraulic energy for each user of an aircraft. Centralized hydraulic energy systems based on three or four sets of fault tolerant designs have become typical configurations of civil aircraft hydraulic systems. With the development of large airliners, the disadvantages of centralized hydraulic systems are not negligible, and the proportion of long pipelines to the total weight of the hydraulic system of the aircraft is increasing. The electric hydraulic energy system can be arranged nearby a user and is provided with the control unit, so that the overall weight of the aircraft can be reduced, and the reliability and maintainability of the aircraft are greatly improved by the distributed layout. In recent years, three sets of distributed electric hydraulic energy systems are adopted as standby hydraulic sources of a front wheel steering system and a braking system. In this case, the safety of the flight is not allowed to be compromised by a single fault. The coexistence of multiple energy sources can cause the problems of bulkiness of the internal structure of the aircraft, tension in installation space, inconvenience in overhaul and maintenance, easiness in leakage of hydraulic energy and pneumatic energy and the like, and can cause high failure rate and poor reliability of the aircraft, so that the performance and reliability of the aircraft are reduced. In view of the above, aircraft hydraulic systems are typically designed as multiple sets of mutually independent redundancy systems, and in the case of higher power applications, a hydraulic and electric actuation combined distributed hydraulic and actuation system, further integrating the distributed hydraulic energy source with the end actuators, forms Electro-hydrostatic actuators (Electro-Hydrostatic Actuator, EHA). An electromechanical actuation system is used in the main flight control actuation system of 1/3 or more. The electromechanical actuating system is an actuating mechanism of the fly-by-wire system of the airplane, is an important component part in the flight control system, mainly comprises an EHA and an electric backup hydraulic servo actuator (EBHA), and has the same core technology as the EHA. The application of the EHA/EBHA enhances the self-checking capability of the aircraft, improves the reliability, reduces the external maintenance requirement, and greatly reduces the required maintenance equipment and maintenance workload. With the rise of technical maturity, centralized hydraulic systems based on engine driven pumps will be gradually replaced by electrically driven distributed hydraulic systems.

There are mainly two forms of power electric actuators, namely electro-hydraulic actuators (EHA) and electro-mechanical actuators (EMA). EHA and EMA are drive-by-wire systems, the core of which is motor control, but the differences between the speed reduction mechanisms are caused by the differences. The EHA uses a reversible hydraulic pump, and the piston is pushed to move by the hydraulic oil in the EHA so as to control the deflection of a control surface connected with the EHA. The EMA is an electromechanical servo system, controls the rotating speed of a motor, drives a speed reduction transmission mechanism, realizes torque output and drives a load. The carrying capacity of the EMA and the speed reduction transmission mechanism are relatively large. The EMA omits a hydraulic system in the actuator, and the motor is directly used for pushing the deflection of the control surface through a gear, a ball screw and other transmission mechanisms. EMA has the following advantages over EHA:

(1) Because of no internal hydraulic system, compared with the EHA with the same power level, the EMA has lighter mass and smaller volume, thereby greatly saving fuel and reducing the take-off mass and the cooling burden of the aircraft;

(2) The elimination of the low efficiency pump, EMA is more easily achieved with higher efficiency:

(3) EMA is more suitable for long-term storage because of the absence of risk of hydraulic oil slip.

The EMA is used for adjusting the output power of the system by controlling the output power of the motor, and the peak value requirement in the load working condition is met by using the short-time overload of the motor. Because brushless motors can be adopted in the EMA, the brushless motors have no mechanical brushes and can bear large overload, and therefore, the use maintainability and reliability of the telex servo system are improved compared with those of the traditional hydraulic system. In addition, the EMA completely cancels the hydraulic link and directly converts the electric energy into mechanical energy. EMA is used as a main flight control surface driving device, and multiple EMAs are backed up to form a synchronous control system of multiple electromechanical actuators, so that the synchronous driving control problem of the multiple electromechanical actuators is avoided.

Electromechanical actuators (EMA) are critical components of flight control systems whose reliability directly affect the flight safety of an aircraft. An electromechanical actuator (EMA) is an electromechanical integrated device, and the electromechanical actuator is an energy conversion device for realizing linear reciprocating motion or less than 360 ° swinging motion of a working mechanism as a linear motion actuator. The EMA converts the output command signals of the servo controller/driver into mechanical quantities such as speed, displacement, load and the like so as to realize the purposes of speed driving, displacement driving and load driving of a control object. The basic constitution of a typical electromechanical actuator is as follows: the device comprises a controller, a driver, a motor, a reduction gearbox, a transmission part, a ball screw pair, a cylinder barrel assembly, a piston rod assembly and the like, and a corresponding sensor assembly. In operation of the actuator system, the position and speed of each actuator are required to be synchronous, if the position and speed of two channels and other state differences can cause different output forces, the channel interaction electromechanical actuators (EMA) are key components of the flight control system, and the reliability of the electromechanical actuators directly influences the flight safety of an aircraft. Searching for an equilibrium position also creates a force fighting phenomenon that reduces the accuracy and reliability of the output of the system, long-term unsynchronized operation can cause damage to the drive and driven components, and even complete failure of the system, thereby leading to synchronous controller introduction in the actuator system. The controller controls the input current of the motor according to the instruction. The motor converts energy, converts electric energy into mechanical energy, converts rotary motion into linear motion, and outputs speed and magnitude to control the motion of the load. If the screw rod and the nut in the actuating cylinder are jammed in the process of swinging the load, the actuating rod cannot stretch and retract any more, the load cannot be pushed any more, and catastrophic failure is likely to occur. For a system with complex working conditions and changeable load, the combination and interference effect caused by uncertainty among all synchronous sub-channels cannot be ignored, so that a single control mode is difficult to obtain a satisfactory synchronous control effect. In practical application, the system has variable load and variable impact disturbance, and if a master-slave mode is adopted, the synchronous control precision is difficult to ensure. While "equivalent" can solve the above problem, the 3-channel coupling is difficult to overcome in practical applications. It is difficult to meet the driving precision requirement by adopting a single control mode of 'equivalent' or 'master-slave'. The master-slave mode refers to a mode that a plurality of executing elements needing synchronous control take the output quantity of one of the executing elements as ideal input, and the other executing elements track the selected ideal input to achieve synchronous driving. "equivalent" means that multiple actuators requiring synchronous control track the same ideal input simultaneously. Both synchronous control modes are applied in practice. But is only limited to occasions with small difference of performances of all channels, simple working conditions and small load change. For a system with complex working conditions and variable loads, the control and interference effects caused by uncertainty among all synchronous sub-channels cannot be ignored, so that a single control mode is difficult to obtain a satisfactory synchronous control effect.

Although the electromechanical actuator EMA cannot be compared with an electrohydraulic actuator at the load bearing limit, the electromechanical actuator EMA has simpler structure and no hydraulic oil leakage problem. In some application occasions with limited installation space or longer working stroke requirements, such as retraction and extension of an undercarriage, retraction of a cabin door and the like, a common single-stage electromechanical actuator cannot meet the limited installation space requirements due to longer overall dead structure length, so that the practicability is poor.

Disclosure of Invention

Aiming at the defects existing in the prior art, the utility model provides a multi-stage step-by-step actuating motor electric actuator scheme which has the advantages of simple structure, safety, reliability, good step-by-step actuating controllability and high control precision, and can realize small installation space and large working stroke. The problem that the dead structure of a conventional single-stage electromechanical actuator is long in length and limited in installation space is effectively solved.

The technical scheme adopted for solving the technical problems is as follows: a multi-stage step-by-step actuator electric actuator comprising: the main transmission gear 2 meshed with the output gear is sleeved on a main screw nut 6 on a main screw barrel 4, and a primary piston rod 10 which moves up and down in the cylinder barrel 3 is characterized in that: the primary servo motor 1 drives a primary screw rod cylinder 4 to rotate through a primary transmission gear 2, the primary screw rod cylinder 4 drives a secondary screw rod 8, the front stepped hole bearing accommodating cavity of which is restrained by a bidirectional thrust angular contact ball bearing 7 and a secondary screw rod nut 9, to perform axial linear telescopic motion in the motion cavity of a secondary piston rod 11 through a primary screw rod nut 6, the stepped hole of which is embedded and restrained at the bottom of a primary piston rod 10; the secondary servo motor 12 is meshed with a shaft end gear of the transmission shaft 14 through the auxiliary transmission gear 13, the transmission shaft 14 drives the auxiliary screw rod 8 sleeved by the circumferential spline to do rotary motion together, the auxiliary screw rod nut 9 is driven to do axial motion, the transmission shaft 14 is meshed with the auxiliary screw rod 8 to do synchronous rotation together through the circumferential spline extending out of the outer ring surface of the cylinder body of the port of the main screw rod cylinder 4, in the centralized step-by-step motion, the main screw rod cylinder 4 can be driven by the primary servo motor 1 through the main screw rod nut 6, the auxiliary screw rod 8 can be driven by the secondary servo motor 12 to do free rotation through the auxiliary screw rod nut 9, two relatively independent transmission chains are respectively formed, the primary piston rod 10 is driven to do linear telescopic motion in the motion cavity of the cylinder barrel 3, and the secondary piston rod 11 is driven to do at least two transmission chain free rotation channels of step-by step motion of telescopic motion in the motion cavity of the primary piston rod 10.

Compared with the prior art, the utility model has the following gain effects:

the utility model adopts a primary servo motor 1 with an output gear assembled on a gear transmission box at one side end of a cylinder barrel 3, a secondary servo motor 12 at the lower end side, a main transmission gear 2 meshed with the output gear, a main screw barrel 4 meshed with the main transmission gear 2, a main screw nut 6 sleeved on the main screw barrel 4 through a transmission shaft 14 assembled by the main screw barrel 4, and a primary piston rod 10 embedded on the main screw nut 6 and making telescopic movement in the cylinder barrel 3, thus the multi-stage step-by-step actuating motor electric actuator is simple in structure and can realize small installation space. The servo motor is used as a power unit of the electromechanical actuator system, so that the step-by-step actuation controllability is good, and the step-by-step actuation control precision is high; the electric cylinder is used as an actuating mechanism of the system, and is driven by a ball screw pair, so that the electric cylinder has the advantages of small friction, less heating, small dynamic error, accurate position control, safety and reliability.

According to the utility model, the auxiliary screw rod 8 which can bear load and can be driven to freely rotate is axially assembled on the main screw rod nut 6, so that the main screw rod cylinder 4 can be driven by the primary servo motor 1, the auxiliary screw rod 8 can be respectively driven by the secondary servo motor 11 to drive the primary piston rod 10 and the secondary piston rod 11 to make telescopic movement, two relatively independent transmission chains are formed, the working stroke of the electromechanical actuator is greatly increased, and the problems of long dead structure length and limited installation space of the conventional single-stage electromechanical actuator are effectively solved. The primary servo motor 1 and the secondary servo motor 12 can also drive the primary piston rod 10 and the secondary piston rod 11 to act step by step, so that complex application conditions can be met. The structure length of the electromechanical actuator can be greatly reduced under the specified stroke, or the working stroke can be greatly increased under the specified structure length.

According to the utility model, the main screw rod cylinder 4 can be driven by the primary servo motor 1, the auxiliary screw rod 8 which can freely rotate is driven by the main screw rod nut 6 to axially move, and the auxiliary screw rod 8 can be driven by the secondary servo motor 12 to freely rotate, so that two relatively independent transmission chains of the primary piston rod 10 and the secondary piston rod 11 for telescopic movement are respectively formed. The output shaft of the motor drives the ball screw to rotate through the speed reducer, the ball screw converts the rotation of the screw into the linear motion of the nut, and the screw sleeve connected with the nut, namely the piston rod of the electric cylinder can output linear displacement. The two independent motor-oil pump assemblies are adopted, so that output command signals of the servo controller/driver can be converted into mechanical quantities such as speed, displacement, load and the like, the probability of common-mode faults of the same type is greatly reduced, and the reliability of the actuator is improved. In addition, by adopting the mutually independent fault monitoring, detecting and fault switching devices, the self-monitoring can be easily participated by means of a computer, the problems of complex force fighting, coupling decoupling and the like can be avoided, and the engineering is easy to realize.

Drawings

FIG. 1 is a schematic longitudinal cross-sectional view of a multistage step actuator electric actuator of the present utility model in a retracted state;

FIG. 2 is a schematic view of the piston rod of FIG. 1 in an extended configuration;

FIG. 3 is a schematic illustration of the splined engagement of the drive shaft 14 of FIG. 1 with the lead screw 8;

in the figure: the device comprises a first-stage servo motor, a main transmission gear, a 3 cylinder barrel, a 4 main screw barrel, a 5 thrust angular contact ball bearing, a 6 main screw nut, a 7 bidirectional thrust angular contact ball bearing, an 8-pair screw, a 9-pair screw nut, a 10-stage piston rod, an 11-stage piston rod, a 12-stage servo motor, a 13-pair transmission gear and a 14 transmission shaft.

The utility model will be further described with reference to the drawings and examples, without thereby restricting the utility model to the scope of the examples. All such concepts should be considered as being generic to the disclosure herein and to the scope of the utility model.

Detailed Description

See fig. 1-3. In a preferred embodiment described below, a multi-stage step-actuation electromechanical actuator comprises: a primary servo motor 1 with an output gear assembled on one side end gear transmission box of a cylinder 3 and a secondary servo motor 12 with a lower end side as secondary transmission, a main transmission gear 2 meshed with the output gear, a main screw nut 6 sleeved on a main screw barrel 4, and a primary piston rod 10 moving up and down in the cylinder 3, wherein: the primary servo motor 1 drives a primary screw rod cylinder 4 to rotate through a primary transmission gear 2, the primary screw rod cylinder 4 drives a secondary screw rod 8, the front stepped hole bearing accommodating cavity of which is restrained by a bidirectional thrust angular contact ball bearing 7 and a secondary screw rod nut 9, to perform axial linear telescopic motion in the motion cavity of a secondary piston rod 11 through a primary screw rod nut 6, the stepped hole of which is embedded and restrained at the bottom of a primary piston rod 10; the secondary servo motor 12 is meshed with a shaft end gear of the transmission shaft 14 through the auxiliary transmission gear 13, the transmission shaft 14 drives the auxiliary screw rod 8 sleeved by the circumferential spline to do rotary motion together, the auxiliary screw rod nut 9 is driven to do axial motion, the transmission shaft 14 is meshed with the auxiliary screw rod 8 to do synchronous rotation together through the circumferential spline extending out of the outer ring surface of the cylinder body of the port of the main screw rod cylinder 4, in the centralized step-by-step motion, the main screw rod cylinder 4 can be driven by the primary servo motor 1 through the main screw rod nut 6, the auxiliary screw rod 8 can be driven by the secondary servo motor 12 to do free rotation through the auxiliary screw rod nut 9, two relatively independent transmission chains are respectively formed, the primary piston rod 10 is driven to do linear telescopic motion in the motion cavity of the cylinder barrel 3, and the secondary piston rod 11 is driven to do at least two transmission chain free rotation channels of step-by step motion of telescopic motion in the motion cavity of the primary piston rod 10.

The sum of the action strokes of the first-stage piston rod 10 which performs telescopic movement in the moving cavity of the cylinder barrel 3 and the second-stage piston rod 11 which performs telescopic movement in the moving cavity of the first-stage piston rod 10 is the total action stroke of the centralized step-by-step action of the actuator.

The main screw rod cylinder 4 is loaded by a thrust angular contact ball bearing 5 assembled through a hollow stepped hole in the end wall of the bottom of the cylinder barrel 3, and simultaneously is loaded by a bidirectional thrust angular contact ball bearing 7 constrained by an H-shaped cylinder of an auxiliary screw rod 8 assembled by a main screw rod nut 6 and an auxiliary screw rod nut 9 sleeved on the auxiliary screw rod 8.

The inner ring of the bidirectional thrust angular contact ball bearing 7 arranged in the hollow stepped hole of the main screw nut 6 is axially limited in the I-shaped cylinder annular groove of the auxiliary screw 8 and the hollow inner wall annular groove of the main screw nut 6, and is used for bearing the load of the auxiliary screw 8.

The inner cylinder wall of the screw rod 8 is provided with long spline grooves with the same size as the external splines of the transmission shaft 14 and are meshed with each other, the transmission shaft 14 drives the auxiliary screw rod 8 to synchronously rotate, and the external splines of the transmission shaft 14 slide in the long spline grooves of the inner cylinder wall of the auxiliary screw rod 8.

In the retraction process of the primary piston rod 10, the auxiliary screw nut 9 assembled in the hollow stepped hole of the secondary piston rod 11 sequentially transmits the load to the auxiliary screw 8, the main screw nut 6, the thrust angular contact ball bearing 5 and the main screw barrel 4, and finally to the cylinder barrel 3.

During normal operation, the primary servo motor 1 drives the main screw barrel 4 to rotate through the main transmission gear 2, and then drives the main screw nut 6 to move to the cylinder bottom along the cylinder barrel 3, drives the primary piston rod 10 to extend out of the end face of the stop ring of the end hole of the cylinder barrel 3, and the auxiliary screw 8 drives the auxiliary screw nut 9 to move to the end face of the stop ring of the end hole of the hollow movement cavity of the primary piston rod 10, so that the secondary piston rod 11 is pushed to extend out of the end hole of the hollow movement cavity of the primary piston rod 10.

The primary servo motor 1 and the secondary servo motor 12 can respectively drive the primary piston rod 10 and the secondary piston rod 11 to act step by step so as to meet complex application conditions.

See fig. 2. The secondary servo motor 12 drives the transmission shaft 14 to rotate through the auxiliary transmission gear 13, the transmission shaft 14 is meshed with the auxiliary screw rod 8 through a circumferential spline, the auxiliary screw rod 8 is driven to synchronously rotate, the auxiliary screw rod nut 9 linearly moves along the hollow movement cavity of the primary piston rod 10, the auxiliary screw rod nut 9 is driven to be separated from the main screw rod nut 6, the step barrel at the tail end of the secondary piston rod 11 sleeved on the outer circle of the auxiliary screw rod nut 9 is pushed to the end face of the stop ring at the bottom end hole of the hollow movement cavity of the primary piston rod 10, the secondary piston rod 11 moves to the bottom end of the cavity along the primary piston rod 10, and the secondary piston rod 11 extends out of the stop ring at the bottom end hole of the cavity.

See fig. 3. The inner cylinder wall of the auxiliary screw rod 8 is provided with long spline grooves with the same size as the external splines of the transmission shaft 14 and are meshed with each other, and the external splines of the transmission shaft 14 slide in the long spline grooves of the inner cylinder wall of the auxiliary screw rod 8 to drive the auxiliary screw rod 8 to synchronously rotate.

Other technical schemes can be obtained according to the above embodiments without inventive labor, and equivalent changes within the scope of the utility model should fall within the scope of the utility model.

Claims

1. A multi-stage step-by-step actuator electric actuator comprising: the device is characterized in that a primary servo motor (1) with an output gear and a secondary servo motor (12) with a lower end side serving as a secondary transmission are assembled on a gear transmission box at one side end of a cylinder barrel (3), a main transmission gear (2) meshed with the output gear, a main screw nut (6) sleeved on a main screw barrel (4) and a primary piston rod (10) which moves in a telescopic manner in the cylinder barrel (3) are assembled on the main screw nut, and the device is also characterized in that: the primary servo motor (1) drives the main screw rod cylinder (4) to rotate through the main transmission gear (2), the main screw rod cylinder (4) is embedded with the restrained main screw rod nut (6) through a step hole at the bottom of the primary piston rod (10), and drives the auxiliary screw rod (8) with a front stepped hole bearing accommodating cavity of the main screw rod nut (6) restrained by the rear end surface of the bidirectional thrust angular contact ball bearing (7) and the auxiliary screw rod nut (9), and the auxiliary screw rod (8) axially linearly stretches and contracts in a motion cavity of the secondary piston rod (11); the secondary servo motor (12) is meshed with a shaft end gear of the transmission shaft (14) through the auxiliary transmission gear (13), the transmission shaft (14) drives the auxiliary screw rod (8) sleeved through the circumferential spline to do rotary motion together, the auxiliary screw rod nut (9) is driven to do axial motion, the transmission shaft (14) is meshed with the auxiliary screw rod (8) through the circumferential spline extending out of the outer annular surface of the port cylinder body of the primary screw rod cylinder (4) to do synchronous rotation together, in the concentrated step-by-step motion, the primary screw rod cylinder (4) can be driven by the primary servo motor (1) through the primary screw rod nut (6), the auxiliary screw rod (8) can be driven by the secondary servo motor (12) to freely rotate through the auxiliary screw rod nut (9), two relatively independent transmission chains are respectively formed, the primary piston rod (10) is driven to do linear telescopic motion in the motion cavity of the cylinder barrel (3), and the secondary piston rod (11) is driven to do at least two transmission chains to freely rotate in the step-by step motion of telescopic motion in the motion cavity of the primary piston rod (10).

2. The multi-stage step-actuation electromechanical actuator according to claim 1, wherein: the main screw barrel (4) is borne by a thrust angular contact ball bearing (5) assembled through a hollow step hole in the bottom end wall of the cylinder barrel (3), and is borne by a bi-directional thrust angular contact ball bearing (7) constrained by an H-shaped barrel of an auxiliary screw (8) assembled by a main screw nut (6) and an auxiliary screw nut (9) sleeved on the auxiliary screw (8).

3. The multi-stage step-actuation electromechanical actuator according to claim 2, wherein: the inner ring of the bidirectional thrust angular contact ball bearing (7) arranged in the hollow stepped hole of the main screw nut (6) is axially limited in the I-shaped cylinder annular groove of the auxiliary screw (8) and the hollow inner wall annular groove of the main screw nut (6), so as to bear the load of the auxiliary screw (8).

4. The multi-stage step-actuation electromechanical actuator according to claim 1, wherein: the inner cylinder wall of the auxiliary screw rod (8) is provided with long spline grooves which are equivalent to the outer spline of the transmission shaft (14) in size and are meshed with each other, the transmission shaft (14) drives the auxiliary screw rod (8) to synchronously rotate, and the outer spline of the transmission shaft (14) slides in the long spline grooves of the inner cylinder wall of the auxiliary screw rod (8).

5. The multi-stage step-actuation electromechanical actuator according to claim 1, wherein: the auxiliary screw nut (9) assembled in the hollow stepped hole of the secondary piston rod (11) sequentially transmits load to the auxiliary screw (8), the main screw nut (6), the thrust angular contact ball bearing (5) and the main screw barrel (4), and finally transmits the load to the cylinder barrel (3).

6. The multi-stage step-actuation electromechanical actuator according to claim 1, wherein: the secondary servo motor (12) drives the transmission shaft (14) to rotate through the auxiliary transmission gear (13), the transmission shaft (14) is meshed with the auxiliary screw rod (8) through the circumferential spline, the auxiliary screw rod (8) is driven to synchronously rotate, the auxiliary screw rod nut (9) moves linearly along the hollow movement cavity of the primary piston rod (10), the auxiliary screw rod nut (9) is driven to be separated from the main screw rod nut (6), the step barrel at the tail end of the secondary piston rod (11) sleeved with the outer circle of the auxiliary screw rod nut (9) is pushed to the end face of the stop ring at the bottom end hole of the hollow movement cavity of the primary piston rod (10), the secondary piston rod (11) moves to the bottom end of the cavity along the primary piston rod (10), and the stop ring hole at the bottom end of the cavity extends out.

7. The multi-stage step-actuation electromechanical actuator according to claim 1, wherein: the inner cylinder wall of the auxiliary screw rod (8) is provided with long spline grooves which are equivalent to the outer spline of the transmission shaft (14) in size and are meshed with each other, the outer spline of the transmission shaft (14) slides in the long spline groove of the inner cylinder wall of the auxiliary screw rod (8), and the auxiliary screw rod (8) is driven to synchronously rotate.