Ultra-Short Electromechanical Servo Mechanism for Mechanical Fault Self-Recovery

Abstract

An ultra-short electromechanical servo mechanism for mechanical fault self-recovery. Two sets of lead screw transmission components having the same lead parameters and bearing capacity are redundantly and coaxially arranged, and are powered by a single servo motor set. A lead screw roll limiting electromagnetic clutch and a nut roll limiting electromagnetic clutch are used for realizing fault isolation when a primary lead screw pair is stuck or jammed. Meanwhile, a standby bearing lead screw pair is started to synchronously complete mechanical fault self-recovery.

Claims

1. An ultra-short mechanical fault self-recovery electromechanical servo mechanism, comprising: a servo motor assembly, a primary work roller screw pair assembly, a secondary work roller screw pair assembly, a lead screw roll limiting electromagnetic clutch assembly, a nut roll limiting electromagnetic clutch assembly and an external connection assembly, wherein the servo motor assembly is mounted coaxially with the primary work roller screw pair assembly; a lead screw of the secondary work roller screw pair assembly has a first end secured to an interior of the external connection assembly, and a second end matingly connected to a lead screw of the primary work roller screw pair assembly; the lead screw roll limiting electromagnet clutch assembly is provided at an power output end of the primary work roller screw pair assembly, and the nut roll limiting electromagnetic clutch assembly is provided on the secondary work roller screw pair assembly; the lead screw roll limiting electromagnetic clutch assembly, the nut roll limiting electromagnetic clutch assembly, and the secondary work roller screw pair assembly are inoperative in a non-fault mode; in a normal operation, the servo motor assembly drives the primary work roller screw pair assembly to output power, and under a constraint of the lead screw roll limiting electromagnetic clutch assembly, the primary work roller screw pair assembly outputs an axial reciprocating movement, and no power is provided for the secondary work roller screw pair assembly; and when the primary work roller screw pair assembly experiences a mechanical transmission failure, a fault self-recovery mode is entered, the lead screw roll limiting electromagnetic clutch assembly and the nut roll limiting electromagnetic clutch assembly are activated simultaneously, such that the servo motor assembly drives the primary work roller screw pair assembly and the secondary work roller screw pair assembly to rotate together, the primary work roller screw pair assembly becomes a static load-bearing connection, and the secondary work roller screw pair assembly realize conversion of rotation to linear output to the external connection assembly, completing mechanical fault self-recovery.

2. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 1, wherein the servo motor assembly comprises a motor rotor, a motor stator, a motor inner housing, a motor front bearing seat, and a motor front end cap; a permanent magnet is affixed to a surface of the motor rotor; the motor stator is mounted in the motor inner housing and mounted coaxially with the motor rotor, and the motor front bearing seat is mounted to an end of the motor inner housing.

3. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 2, wherein the servo motor assembly further comprises a primary clutch connection toothed disc and a secondary clutch connection toothed disc; the primary work roller screw pair assembly comprises an internal-thread end-face-tooth long nut, a hollow long shaft lead screw, a first roller and a first cage; the motor rotor is mounted on the internal-thread end-face-tooth long nut, and two ends of the internal-thread end-face-tooth long nut are respectively mounted on a bearing seat in the motor inner housing and the motor front bearing seat through a bearing; the two ends of the internal-thread end-face-tooth long nut are respectively mounted with the primary clutch connection toothed disc and the secondary clutch connection toothed disc; the hollow long shaft lead screw has a first end mounted with the first roller, and the first roller is mounted in the internal-thread end-face-tooth long nut to constitute a primary work roller screw pair, the first cage is provided at each end of the first roller, and the hollow long shaft lead screw has a second end extending out from a center hole of the primary clutch connection toothed disc.

4. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 3, wherein the external connection assembly comprises an outer casing and a front end cap bolt; the lead screw roll limiting electromagnetic clutch assembly is mounted to the second end of the hollow long shaft lead screw extending out from the center hole of the primary clutch connection toothed disc, located in the motor front bearing seat, and mated with the primary clutch connection toothed disc; and an end of the motor front bearing seat is mounted with the motor front end cap and secured using the front end cap bolt; and the motor inner housing and the motor front bearing seat are mounted in the outer casing, and the motor front bearing seat is located at an open end of the outer casing.

5. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 4, wherein the external connection assembly further comprises a rear end cap bolt; the secondary work roller screw pair assembly comprises an internal-thread spline-tooth short nut, a solid long shaft lead screw, a second roller, and a second cage; the solid long shaft lead screw has a first end fixedly connected to an inner end face of a closed end of the outer casing through the rear end cap bolt to limit rotation of the solid long shaft lead screw and cause a relative movement of the solid long shaft lead screw in an axis direction, and the solid long shaft lead screw has a second end inserted into a center hole of the hollow long shaft lead screw; the second roller is mounted to the solid long shaft lead screw and located at an outer side of the secondary clutch connection toothed disc; the internal-thread spline-tooth short nut is mounted at a periphery of the second roller, to constitute a secondary work roller screw pair; and the second cage is provided at an end of the second roller; and the nut roll limiting electromagnetic clutch assembly is mounted to the internal-thread spline-tooth short nut, and mated with the secondary clutch connection toothed disc.

6. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 5, wherein the lead screw roll limiting electromagnetic clutch assembly comprises a roll limiting spline rotary sleeve, a first movable double sided spline toothed disc, a first electromagnetic attraction coil, a first reset spring, a first fixed end face toothed disc, and a first bearing fixing seat; and the roll limiting spline rotary sleeve is mounted to the second end of the hollow long shaft lead screw extending out from the center hole of the primary clutch connection toothed disc, a center hole of the roll limiting spline rotary sleeve is a slotted hole, two sections extending in a longitudinal direction are symmetrically provided on the hollow long shaft lead screw and mated with the center hole of the roll limiting spline rotary sleeve; the first movable double sided spline toothed disc and the roll limiting spline rotary sleeve are mated with an internal spline hole and an external spine shaft to transmit a rotational movement and reciprocate along the axial direction of the hollow long shaft lead screw; the first bearing fixing seat is mounted to the roll limiting spline rotary sleeve through a deep groove ball bearing to rotate relative to the roll limiting spline rotary sleeve, the first fixed end face toothed disc is fitted over the first bearing fixing seat, and the first reset spring is compressed in opposite holes of the first movable double sided spline toothed disc and a first side of the first fixed end face toothed disc, to perform a reset disengagement action on the first movable double sided spline toothed disc; flange end faces of the first bearing fixing seat and the first fixed end face toothed disc are jointly secured to an inner wall of the motor front bearing seat; and the first electromagnetic attraction coil is mounted in an annular groove of a second side of the first fixed end face toothed disc, to perform electromagnetic attraction on the first movable double sided spline toothed disc.

7. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 6, wherein the lead screw roll limiting electromagnetic clutch assembly controls clutch switching of rotational movement of the primary work roller screw pair by energizing or de-energizing the first electromagnetic attraction coil; when the first electromagnetic attraction coil is de-energized, the first movable double sided spline toothed disc is engaged with the primary clutch connection toothed disc and disengaged from the first fixed end face toothed disc simultaneously, the first movable double sided spline toothed disc utilizes an internal and external spine connection to drive the roll limiting spline rotary sleeve to rotate together, and the roll limiting spline rotary sleeve drives the hollow long shaft lead screw to rotate together, such that the primary work roller screw pair assembly cannot output a linear movement; and when the first electromagnetic attraction coil is energized, the first movable double sided spline toothed disc is disengaged from the primary clutch connection toothed disc and engaged with the first fixed end face toothed disc simultaneously, the roll limiting spline rotary sleeve is immobilized with the first fixed end face toothed disc, and the roll limiting spline rotary sleeve constrains the hollow long shaft lead screw to move in the axial direction, such that the primary work roller screw pair assembly outputs the linear movement.

8. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 6, wherein the nut roll limiting electromagnetic clutch assembly comprises a second movable double sided spline toothed disc, a second electromagnetic attraction coil, a second reset spring, a second fixed end face toothed disc, and a second bearing fixing seat; and the second movable double sided spline toothed disc and the internal-thread spline-tooth short nut are mated with an internal spline hole and an external spine shaft to transmit a rotational movement and reciprocate along the axial direction; the second bearing fixing seat is mounted to the internal-thread spline-tooth short nut through an angular contact ball bearing to rotate relative to the internal-thread spline-tooth short nut; the second fixed end face toothed disc is fitted over the second bearing fixing seat, and the second reset spring is compressed in opposite holes of the second movable double sided spline toothed disc and a first side of the second fixed end face toothed disc, to perform a reset disengagement action on the second movable double sided spline toothed disc; flange end faces of the second bearing fixing seat and the second fixed end face toothed disc are jointly secured to an inner wall of the motor inner housing; and the second electromagnetic attraction coil is mounted in an annular groove of a second side of the second fixed end face toothed disc, to perform electromagnetic attraction on the second movable double sided spline toothed disc.

9. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 8, wherein the nut roll limiting electromagnetic clutch assembly controls clutch switching of rotational movement of the secondary work roller screw pair assembly by energizing or de-energizing the second electromagnetic attraction coil; when the second electromagnetic attraction coil is de-energized, the second movable double sided spline toothed disc is engaged with the secondary clutch connection toothed disc and disengaged from the second fixed end face toothed disc simultaneously, the second movable double sided spline toothed disc utilizes an internal and external spine connection to drive the internal-thread spline-tooth short nut to rotate together, such that the solid long shaft lead screw outputs reciprocating linear movement; and when the second electromagnetic attraction coil is energized, the second movable double sided spline toothed disc is disengaged from the secondary clutch connection toothed disc and engaged with the second fixed end face toothed disc simultaneously, power of the servo motor assembly cannot be transferred to the secondary work roller screw pair assembly, and threads of the internal-thread spline-tooth short nut, the solid long shaft lead screw, and the second roller only bear load statically without action.

10. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 9, wherein in the lead screw roll limiting electromagnetic clutch assembly and the nut roll limiting electromagnetic clutch assembly, power is supplied to the first electromagnetic attraction coil and the second electromagnetic attraction coil synchronously, to ensure that the first movable double sided spline toothed disc and the second movable double sided spline toothed disc attract or disengage from the primary clutch connection toothed disc and the secondary clutch connection toothed disc synchronously and realize handling and self-recovery of screw jamming/stuck mechanical fault.

11. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 4, wherein an inner cavity of the outer casing has a cuboid structure, the motor inner housing has a cuboid shape, and the outer casing and the motor inner housing are mated with each other to limit rolling of a servo motor.

12. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 4, wherein the external connection assembly further comprises a front end lug and a bearing steel ball; the bearing steel ball is mounted between the hollow long shaft lead screw and the front end lug for cyclic rolling; when the primary work roller screw pair assembly outputs the linear movement, the hollow long shaft lead screw and the front end lug do not rotate relative to each other and can only reciprocate, extend and retract along the axis; and when the secondary work roller screw pair assembly outputs the linear movement, the hollow long shaft lead screw and the front end lug rotate relative to each other and reciprocate, extend and retract along the axis.

13. The ultra-short mechanical fault self-recovery electromechanical servo mechanism according to claim 1, wherein the primary work roller screw pair assembly has a reciprocating linear travel of 2, and the secondary work roller screw pair assembly has a reciprocating linear travel of 4.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a diagram of an internal composition of an ultra-short mechanical fault self-recovery electromechanical servo mechanism provided by an embodiment of the present disclosure;

[0009] FIG. 2 is a schematic diagram of an appearance of an ultra-short mechanical fault self-recovery electromechanical servo mechanism provided by an embodiment of the present disclosure; and

[0010] FIG. 3 is a schematic diagram of a movable double sided spline toothed disc of an ultra-short mechanical fault self-recovery electromechanical servo mechanism provided by an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0011] The present disclosure is described with reference to the drawings.

[0012] As illustrated in FIG. 1, an ultra-short mechanical fault self-recovery electromechanical servo mechanism includes a servo motor assembly, a primary work roller screw pair assembly, a secondary work roller screw pair assembly, a lead screw roll limiting electromagnetic clutch assembly, a nut roll limiting electromagnetic clutch assembly and an external connection assembly.

[0013] The external connection assembly includes a front end lug 6a, an outer casing 6b, a bearing steel ball 6c, a front end cap bolt 6d, and a rear end cap bolt 6e.

[0014] The servo motor assembly includes a motor rotor 1a, a motor stator 1b, a motor inner housing 1c, a motor front bearing seat 1d, a motor front end cap 1e, a primary clutch connection toothed disc 1f, and a secondary clutch connection toothed disc 1g.

[0015] A permanent magnet is affixed to a surface of the motor rotor 1a of the servo motor assembly, the motor stator 1b is mounted coaxially with the motor rotor 1a, and mounted in the motor inner housing 1c through an interference connection, and the motor front bearing seat 1d is mounted to an end of the motor inner housing 1c; the motor inner housing 1c and the motor front bearing seat 1d are mounted in the outer casing 6b, and the motor front bearing seat 1d is located at an open end of the outer casing 6b; and [0016] the primary work roller screw pair assembly includes an internal-thread end-face-tooth long nut, a hollow long shaft lead screw 2b, a first roller 2c and a first cage 2d. The motor rotor 1a is mounted on the internal-thread end-face-tooth long nut 2a, and two ends of the internal-thread end-face-tooth long nut 2a are respectively mounted on a bearing seat in the motor inner housing 1c and the motor front bearing seat 1d through a bearing; the two ends of the internal-thread end-face-tooth long nut 2a are respectively mounted with the primary clutch connection toothed disc 1f and the secondary clutch connection toothed disc 1g; the hollow long shaft lead screw 2b has a first end mounted with the first roller 2c, and the first roller 2c is mounted in the internal-thread end-face-tooth long nut 2a to constitute a primary work roller screw pair, the first cage 2d is provided at each end of the first roller 2c, and the hollow long shaft lead screw 2b has a second end extending out from a center hole of the primary clutch connection toothed disc 1f; and [0017] the internal-thread end-face-tooth long nut 2a, the first roller 2c, the first cage 2d, and the hollow long shaft lead screw 2b are arranged coaxially from outside to inside, and constitute the primary work roller screw pair through a thread meshing principle. The internal-thread end-face-tooth long nut 2a is driven by the servo motor assembly and undergoes rotational movement, and when the hollow long shaft lead screw 2b is restricted to move only in the axial direction, several first rollers 2c undergoes cyclic rotation under a constraint of the first cage 2d, to convert rotation of a servo motor to a linear output.

[0018] It should be noted that the internal-thread end-face-tooth long nut 2a herein refers to a long nut having internal threads and end face teeth.

[0019] The secondary work roller screw pair assembly includes an internal-thread spline-tooth short nut 3a, a solid long shaft lead screw 3b, a second roller 3c, and a second cage 3d. The solid long shaft lead screw 3b has a first end fixedly connected to an inner end face of a closed end of the outer casing 6b through the rear end cap bolt 6e to limit rotation of the solid long shaft lead screw 3b and cause a relative movement of the solid long shaft lead screw 3b in an axis direction, and the solid long shaft lead screw 3b has a second end inserted into a center hole of the hollow long shaft lead screw 2b; the second roller 3c is mounted to the solid long shaft lead screw 3b and located at an outer side of the secondary clutch connection toothed disc 1g; the internal-thread spline-tooth short nut 3a is mounted at a periphery of the second roller 3c, to constitute a secondary work roller screw pair; and the second cage 3d is provided at an end of the second roller 3c; and [0020] the internal-thread spline-tooth short nut 3a, the second roller 3c, the second cage 3d and the solid long shaft lead screw 3b are arranged coaxially from outside to inside, and constitute the secondary work roller screw pair through the thread meshing principle. When the internal-thread spline-tooth short nut 3a is driven by the servo motor assembly and undergoes the rotational movement, the second roller 3c and the second cage 3d undergo cyclic rotation to force the solid long shaft lead screw 3b to convert the rotation of the servo motor to the linear output.

[0021] It should be noted that the internal-thread spline-tooth short nut 3a herein refers to a short nut having internal threads and spline teeth.

[0022] The lead screw roll limiting electromagnetic clutch assembly includes a roll limiting spline rotary sleeve 4a, a first movable double sided spline toothed disc 4b, a first electromagnetic attraction coil 4c, a first reset spring 4d, a first fixed end face toothed disc 4e, and a first bearing fixing seat 4f. The roll limiting spline rotary sleeve 4a is mounted to the second end of the hollow long shaft lead screw 2b extending out from the center hole of the primary clutch connection toothed disc 1f, a center hole of the roll limiting spline rotary sleeve 4a is a slotted hole, two sections extending in a longitudinal direction are symmetrically provided on the hollow long shaft lead screw 2b and mated with the center hole of the roll limiting spline rotary sleeve 4a; the first movable double sided spline toothed disc 4b and the roll limiting spline rotary sleeve 4a are mated with an internal spline hole and an external spine shaft to transmit a rotational movement and reciprocate along the axial direction of the hollow long shaft lead screw 2b; the first electromagnetic attraction coil 4c is mounted in an annular groove of a second side of the first fixed end face toothed disc 4e, to perform electromagnetic attraction action on the first movable double sided spline toothed disc 4b; the first reset spring 4d is located a middle position between the first movable double sided spline toothed disc 4b and the first fixed end face toothed disc 4e, the spring is compressed in corresponding holes of the two parts, and can perform reset disengagement action on the first movable double sided spline toothed disc 4b; the first fixed end face toothed disc 4e is fitted over the first bearing fixing seat 4f, a pair of deep groove ball bearings are mounted to an inner side of the first bearing fixing seat 4f, and the first bearing fixing seat 4f rotates relative to the roll limiting spline rotary sleeve 4a; and flange end faces of the first bearing fixing seat 4f and the first fixed end face toothed disc 4e are jointly secured to an inner wall of the motor front bearing seat 1d through a countersunk head screw assembly; and

[0023] The lead screw roll limiting electromagnetic clutch assembly has a hollow structure and mounted to a movement/power output side of the primary work roller screw pair assembly, and controls clutch switching of rotational movement of the primary work roller screw pair by energizing/de-energizing the first electromagnetic attraction coil 4c; the first movable double sided spline toothed disc 4b is located at a middle coaxial position of the primary clutch connection toothed disc 1f and the first fixed end face toothed disc 4e; when the first electromagnetic attraction coil 4c is de-energized, the first movable double sided spline toothed disc 4b is engaged with a toothed disc with a small diameter of the primary clutch connection toothed disc 1f and disengaged from a toothed disc with a large diameter of the first fixed end face toothed disc 4e simultaneously, utilizes an internal and external spine connection to drive the roll limiting spline rotary sleeve 4a to rotate together, and utilizes a flat shaft/flat hole connection to drive the hollow long shaft lead screw 2b to rotate together, such that the primary work roller screw pair assembly cannot output a linear movement; and when the first electromagnetic attraction coil 4c is energized, the first movable double sided spline toothed disc 4b is disengaged from the toothed disc with the small diameter of the primary clutch connection toothed disc 1f and engaged with the toothed disc with the large diameter of the first fixed end face toothed disc 4e simultaneously, the roll limiting spline rotary sleeve 4a is immobilized with the first fixed end face toothed disc 4e and utilizes the flat shaft/flat hole connection to constrain the hollow long shaft lead screw 2b to move only in the axial direction, such that the primary work roller screw pair assembly outputs the linear movement.

[0024] The nut roll limiting electromagnetic clutch assembly includes a second movable double sided spline toothed disc 5a, a second electromagnetic attraction coil 5b, a second reset spring 5c, a second fixed end face toothed disc 5d, and a second bearing fixing seat 5e. The second movable double sided spline toothed disc 5a and the internal-thread spline-tooth short nut 3a are mated with an internal spline hole and an external spine shaft to transmit a rotational movement and reciprocate along the axial direction; the second electromagnetic attraction coil 5b is mounted in an annular groove of a second side of the second fixed end face toothed disc 5d through an interference fit connection, and can perform electromagnetic attraction action on the second movable double sided spline toothed disc 5a; the second reset spring 5c is located at a middle position between the second movable double sided spline toothed disc 5a and the second fixed end face toothed disc 5d, the spring is compressed in corresponding holes of the two parts and can perform a reset disengagement action on the second movable double sided spline toothed disc 5a; and the second fixed end face toothed disc 5d is fitted over the second bearing fixing seat 5e, a pair of angular contact ball bearings are mounted to an inner side of the second bearing fixing seat 5e, and the second bearing fixing seat 5e rotates relative to the internal-thread spline-tooth short nut 3a; and flange end faces of the second bearing fixing seat 5e and the second fixed end face toothed disc 5d are jointly secured to an inner wall of the motor inner housing 1c through the countersunk head screw assembly; and

[0025] The nut roll limiting electromagnetic clutch assembly has a hollow structure and mounted to a right side of the secondary work roller screw pair assembly, and controls clutch switching of rotational movement of the secondary work roller screw pair assembly by energizing/de-energizing the second electromagnetic attraction coil 5b. The second movable double sided spline toothed disc 5a is located at a middle coaxial position between the secondary clutch connection toothed disc 1g and the second fixed end face toothed disc 5d; when the second electromagnetic attraction coil 5b is de-energized, the second movable double sided spline toothed disc 5a is engaged with a toothed disc with a small diameter of the secondary clutch connection toothed disc 1g and disengaged from a toothed disc of a large diameter of the second fixed end face toothed disc 5d simultaneously, and utilizes an internal and external spine connection to drive the internal-thread spline-tooth short nut 3b to rotate together, such that the solid long shaft lead screw 3b of the secondary work roller screw pair assembly outputs a reciprocating linear movement; and when the second electromagnetic attraction coil 5b is energized, the second movable double sided spline toothed disc 5a is disengaged from the toothed disc with the small diameter of the secondary clutch connection toothed disc 1g and engaged with the toothed disc with the large diameter of the second fixed end face toothed disc 5d simultaneously, power of the servo motor assembly cannot be transferred to the secondary work roller screw pair assembly, and threads of the internal-thread spline-tooth short nut 3a, the solid long shaft lead screw 3b and the second roller 3c only bear load statically without action.

[0026] The first reset spring 4d and the second reset spring 5c are respectively mounted in corresponding seat holes of the first fixed end face toothed disc 4e and the second fixed end face toothed disc 5d, and can perform attraction reset on the first movable double sided spline toothed disc 4b and the second movable double sided spline toothed disc 5a.

[0027] The bearing steel ball 6c is mounted between the hollow long shaft lead screw 2b and the front end lug 6a for cyclic rolling; when the primary work roller screw pair assembly is in an normal operation, the hollow long shaft lead screw 2b and the front end lug 6a do not rotate relative to each other and can only reciprocate, extend and retract along the axis; and when the secondary work roller screw pair assembly is in operation, the hollow long shaft lead screw 2b and the front end lug 6a rotate relative to each other and reciprocate, extend and retract along the axis.

[0028] The outer casing 6b is fixedly flange-coupled to the solid long shaft lead screw 3b by the rear end cap bolt 6e, such that the solid long shaft lead screw 3b cannot rotate and can only move in the axis direction of the mechanism.

[0029] The ultra-short mechanical fault self-recovery electromechanical servo mechanism as a whole has a square appearance structure, is mounted with semi-circular connecting lugs at front and rear sides, an actuator rod can extend out from its square center hole, to achieve the reciprocating extension and retraction movement.

[0030] As illustrated in FIG. 2, an inner cavity of the outer casing 6b has a square structure, an outline of the motor inner housing has a square structure, and their four square faces are mated with each other to limit rolling of a servo motor.

[0031] The secondary work roller screw pair assembly, the nut roll limiting electromagnetic clutch assembly, the servo motor assembly, the primary work roller screw pair assembly, the lead screw roll limiting electromagnetic clutch assembly and the external connection assembly are mounted in a same axis sequentially from a left end to a right end, two clutches are arranged at two sides of a rotating shaft of the motor assembly, linear moving parts of two screw pairs are embedded in each other and do not interfere, and the two clutches and the secondary work roller screw pair assembly is inoperative in a non-fault mode.

[0032] In a normal operation, the servo motor assembly drives the nut of the primary work roller screw pair assembly to rotate for power output, and under a constraint of the lead screw roll limiting electromagnetic clutch assembly, its lead screw cannot rotate and can only reciprocate in the axial direction, no power is provided for the secondary work roller screw pair assembly, and the threads of the screw serve as static load-bearing connection; and when an electromechanical system detects that the primary work roller screw pair assembly experiences a mechanical transmission failure such as thread jamming/stuck, a fault self-recovery mode is switched, the lead screw roll limiting electromagnetic clutch assembly and the nut roll limiting electromagnetic clutch assembly are activated simultaneously, and end face teeth are disengaged and engaged again, such that the motor rotor 1a drives the hollow long shaft lead screw 2b and the internal-thread spline-tooth short nut 3a to rotate together, the primary work roller screw pair assembly becomes a static load-bearing connection, and the secondary work roller screw pair assembly realize conversion of rotation to linear output to the external connection assembly, completing mechanical fault self-recovery.

[0033] The lead screw roll limiting electromagnetic clutch assembly and the nut roll limiting electromagnetic clutch assembly need to supply power to the first electromagnetic attraction coil 4c and the second electromagnetic attraction coil 5b synchronously, to ensure that they attract or disengage from the primary clutch connection toothed disc 1f and the secondary clutch connection toothed disc 1g synchronously and handling and self-recovery of screw jamming/stuck mechanical fault can be only realized if both discs are successfully and accurately controlled simultaneously.

[0034] A pair of support bearings of the servo motor assembly and a pair of support bearings of the secondary work roller screw pair assembly can bear the same load axial force, and have a same upper speed limit requirement, while a pair of support bearings of the lead screw roll limiting electromagnetic clutch assembly cannot bear an axial force, but have the same upper speed limit requirement as the forgoing two.

[0035] The primary work roller screw pair assembly and the secondary work roller screw pair have the same lead parameter, and both can bear the same load axial force and have the same upper speed limit requirement.

[0036] As illustrated in FIG. 3, a spline is provided in the inner wall of the center hole of the first movable double sided spline toothed disc 4b and the second movable double sided spline toothed disc 5a, a ring of teeth is provided on each side face of the disc, and the rings of teeth on the two side faces have different diameters.

[0037] The toothed disc with the small diameter and the toothed disc with the large diameter of the lead screw roll limiting electromagnetic clutch assembly and the nut roll limiting electromagnetic clutch assembly have the same structural design parameters and load bearing capacity.

[0038] The primary work roller screw pair assembly has a reciprocating linear travel of 2, and then the secondary work roller screw pair assembly has a reciprocating linear travel of 4. That is, there is a 2 design relationship between them.

[0039] The technical solutions used in the present disclosure are: an ultra-short mechanical fault self-recovery electromechanical servo mechanism includes a servo motor assembly, a primary work roller screw pair assembly, a secondary work roller screw pair assembly, a lead screw roll limiting electromagnetic clutch assembly, a nut roll limiting electromagnetic clutch assembly and an external connection assembly; [0040] the external connection assembly includes an outer casing, a front end cap bolt, and a rear end cap bolt; [0041] the servo motor assembly includes a motor rotor, a motor stator, a motor inner housing, a motor front bearing seat, a motor front end cap, a primary clutch connection toothed disc, and a secondary clutch connection toothed disc; a permanent magnet is affixed to a surface of the motor rotor; the motor stator is mounted in the motor inner housing, and mounted coaxially with the motor rotor; the motor front bearing seat is mounted to an end of the motor inner housing; [0042] the primary work roller screw pair assembly includes an internal-thread end-face-tooth long nut, a hollow long shaft lead screw, a first roller and a first cage; the motor rotor is mounted on the internal-thread end-face-tooth long nut, and two ends of the internal-thread end-face-tooth long nut are respectively mounted on a bearing seat in the motor inner housing and the motor front bearing seat through a bearing; the two ends of the internal-thread end-face-tooth long nut are respectively mounted with the primary clutch connection toothed disc and the secondary clutch connection toothed disc; the hollow long shaft lead screw has a first end mounted with the first roller, and the first roller is mounted in the internal-thread end-face-tooth long nut to constitute a primary work roller screw pair, the first cage is provided at each end of the first roller, and the hollow long shaft lead screw has a second end extending out from a center hole of the primary clutch connection toothed disc; [0043] the lead screw roll limiting electromagnetic clutch assembly is mounted to the second end of the hollow long shaft lead screw extending out from the center hole of the primary clutch connection toothed disc, located in the motor front bearing seat, and mated with the primary clutch connection toothed disc; and an end of the motor front bearing seat is mounted with the motor front end cap and secured using the front end cap bolt; [0044] the motor inner housing and the motor front bearing seat are mounted in the outer casing, and the motor front bearing seat is located at an open end of the outer casing; [0045] the secondary work roller screw pair assembly includes an internal-thread spline-tooth short nut, a solid long shaft lead screw, a second roller, and a second cage; the solid long shaft lead screw has a first end fixedly connected to an inner end face of a closed end of the outer casing through the rear end cap bolt to limit rotation of the solid long shaft lead screw and cause a relative movement of the solid long shaft lead screw in an axis direction, and the solid long shaft lead screw has a second end inserted into a center hole of the hollow long shaft lead screw; the second roller is mounted to the solid long shaft lead screw and located at an outer side of the secondary clutch connection toothed disc; the internal-thread spline-tooth short nut is mounted at a periphery of the second roller, to constitute a secondary work roller screw pair; and the second cage is provided at an end of the second roller; and [0046] the nut roll limiting electromagnetic clutch assembly is mounted to the internal-thread spline-tooth short nut, and mated with the secondary clutch connection toothed disc.

[0047] Further, the lead screw roll limiting electromagnetic clutch assembly includes a roll limiting spline rotary sleeve, a first movable double sided spline toothed disc, a first electromagnetic attraction coil, a first reset spring, a first fixed end face toothed disc, and a first bearing fixing seat; and [0048] the roll limiting spline rotary sleeve is mounted to the second end of the hollow long shaft lead screw extending out from the center hole of the primary clutch connection toothed disc, a center hole of the roll limiting spline rotary sleeve is a slotted hole, two sections extending in a longitudinal direction are symmetrically provided on the hollow long shaft lead screw and mated with the center hole of the roll limiting spline rotary sleeve; the first movable double sided spline toothed disc and the roll limiting spline rotary sleeve are mated with an internal spline hole and an external spine shaft to transmit a rotational movement and reciprocate along the axial direction of the hollow long shaft lead screw; the first bearing fixing seat is mounted to the roll limiting spline rotary sleeve through a deep groove ball bearing to rotate relative to the roll limiting spline rotary sleeve, the first fixed end face toothed disc is fitted over the first bearing fixing seat, and the first reset spring is compressed in opposite holes of the first movable double sided spline toothed disc and a first side of the first fixed end face toothed disc, to perform a reset disengagement action on the first movable double sided spline toothed disc; flange end faces of the first bearing fixing seat and the first fixed end face toothed disc are jointly secured to an inner wall of the motor front bearing seat; and the first electromagnetic attraction coil is mounted in an annular groove of a second side of the first fixed end face toothed disc, to perform electromagnetic attraction on the first movable double sided spline toothed disc.

[0049] Further, the lead screw roll limiting electromagnetic clutch assembly controls clutch switching of rotational movement of the primary work roller screw pair by energizing or de-energizing the first electromagnetic attraction coil; [0050] when the first electromagnetic attraction coil is de-energized, the first movable double sided spline toothed disc is engaged with the primary clutch connection toothed disc and disengaged from the first fixed end face toothed disc simultaneously, the first movable double sided spline toothed disc utilizes an internal and external spine connection to drive the roll limiting spline rotary sleeve to rotate together, and the roll limiting spline rotary sleeve drives the hollow long shaft lead screw to rotate together, such that the primary work roller screw pair assembly cannot output a linear movement; and [0051] when the first electromagnetic attraction coil is energized, the first movable double sided spline toothed disc is disengaged from the primary clutch connection toothed disc and engaged with the first fixed end face toothed disc simultaneously, the roll limiting spline rotary sleeve is immobilized with the first fixed end face toothed disc, and the roll limiting spline rotary sleeve constrains the hollow long shaft lead screw to move in the axial direction, such that the primary work roller screw pair assembly outputs the linear movement.

[0052] Further, the nut roll limiting electromagnetic clutch assembly includes a second movable double sided spline toothed disc, a second electromagnetic attraction coil, a second reset spring, a second fixed end face toothed disc, and a second bearing fixing seat; and [0053] the second movable double sided spline toothed disc and the internal-thread spline-tooth short nut are mated with an internal spline hole and an external spine shaft to transmit a rotational movement and reciprocate along the axial direction; the second bearing fixing seat is mounted to the internal-thread spline-tooth short nut through an angular contact ball bearing to rotate relative to the internal-thread spline-tooth short nut; the second fixed end face toothed disc is fitted over the second bearing fixing seat, and the second reset spring is compressed in opposite holes of the second movable double sided spline toothed disc and a first side of the second fixed end face toothed disc, to perform a reset disengagement action on the second movable double sided spline toothed disc; flange end faces of the second bearing fixing seat and the second fixed end face toothed disc are jointly secured to an inner wall of the motor inner housing; and the second electromagnetic attraction coil is mounted in an annular groove of a second side of the second fixed end face toothed disc, to perform electromagnetic attraction on the second movable double sided spline toothed disc.

[0054] Further, the nut roll limiting electromagnetic clutch assembly controls clutch switching of rotational movement of the secondary work roller screw pair assembly by energizing or de-energizing the second electromagnetic attraction coil; [0055] when the second electromagnetic attraction coil is de-energized, the second movable double sided spline toothed disc is engaged with the secondary clutch connection toothed disc and disengaged from the second fixed end face toothed disc simultaneously, the second movable double sided spline toothed disc utilizes an internal and external spine connection to drive the internal-thread spline-tooth short nut to rotate together, such that the solid long shaft lead screw outputs reciprocating linear movement; and [0056] when the second electromagnetic attraction coil is energized, the second movable double sided spline toothed disc is disengaged from the secondary clutch connection toothed disc and engaged with the second fixed end face toothed disc simultaneously, power of the servo motor assembly cannot be transferred to the secondary work roller screw pair assembly, and threads of the internal-thread spline-tooth short nut, the solid long shaft lead screw, and the second roller only bear load statically without action.

[0057] Further, in the lead screw roll limiting electromagnetic clutch assembly and the nut roll limiting electromagnetic clutch assembly, power is supplied to the first electromagnetic attraction coil and the second electromagnetic attraction coil synchronously, to ensure that the first movable double sided spline toothed disc and the second movable double sided spline toothed disc attract or disengage from the primary clutch connection toothed disc and the secondary clutch connection toothed disc synchronously and realize handling and self-recovery of screw jamming/stuck mechanical fault.

[0058] Further, an inner cavity of the outer casing has a cuboid structure, the motor inner housing has a cuboid shape, and the outer casing and the motor inner housing are mated with each other to limit rolling of a servo motor.

[0059] Further, the external connection assembly further includes a front end lug and a bearing steel ball; the bearing steel ball is mounted between the hollow long shaft lead screw and the front end lug for cyclic rolling; when the primary work roller screw pair assembly outputs the linear movement, the hollow long shaft lead screw and the front end lug do not rotate relative to each other and can only reciprocate, extend and retract along the axis; and when the secondary work roller screw pair assembly outputs the linear movement, the hollow long shaft lead screw and the front end lug rotate relative to each other and reciprocate, extend and retract along the axis.

[0060] Further, the primary work roller screw pair assembly has a reciprocating linear travel of 2, and the secondary work roller screw pair assembly has a reciprocating linear travel of 4.

[0061] Further, the lead screw roll limiting electromagnetic clutch assembly, the nut roll limiting electromagnetic clutch assembly, and the secondary work roller screw pair assembly are inoperative in a non-fault mode; in a normal operation, the first electromagnetic attraction coil and the second electromagnetic attraction coil are energized simultaneously, the servo motor assembly drives the internal-thread end-face-tooth long nut of the primary work roller screw pair assembly to output power, and under a constraint of the lead screw roll limiting electromagnetic clutch assembly, the hollow long shaft lead screw cannot rotate and can only reciprocate in the axial direction, and no power is provided for the secondary work roller screw pair assembly; and [0062] when the primary work roller screw pair assembly experiences a mechanical transmission failure, a fault self-recovery mode is entered, the first electromagnetic attraction coil and the second electromagnetic attraction coil are de-energized simultaneously, the lead screw roll limiting electromagnetic clutch assembly and the nut roll limiting electromagnetic clutch assembly are activated simultaneously, such that the motor rotor drives the hollow long shaft lead screw and the internal-thread spline-tooth short nut to rotate together, the primary work roller screw pair assembly becomes a static load-bearing connection, and the secondary work roller screw pair assembly realize conversion of rotation to linear output to the external connection assembly, completing mechanical fault self-recovery.

[0063] The advantages of the present disclosure over the related art are: [0064] (1) The ultra-short mechanical fault self-recovery electromechanical servo mechanism proposed by the present disclosure realizes the redundancy design, margin design and fault-tolerant design for the mechanical transmission component, and can carry out fault isolation and recovery work after fault detection and identification. [0065] (2) The ultra-short mechanical fault self-recovery electromechanical servo mechanism proposed by the present disclosure ensures that in a case where the performance of the whole machine is not degraded, miniaturization and integration is aimed, an ultra-short zero position design is performed in a zero position length, and a significant effect on the power density of EMA is ensured. [0066] (3) The ultra-short mechanical fault self-recovery electromechanical servo mechanism proposed by the present disclosure custom-designs a double-sided teeth electromagnetic clutch, with a compact structure, small size and higher torque transmission, and electromagnetic clutch can quickly realize the fault switching, and is suitable for application in the EMA redundant design scheme. [0067] (4) The ultra-short mechanical failure self-recovery electromechanical servo mechanism proposed by the present invention can be expanded and applied to the field of high-reliability and high-safety actuation technology, and has a broader application prospect.

[0068] The undetailed portions of the present disclosure are of common knowledge to those skilled in the art.