Full-closed-loop miniature linear electric drive joint based on reverse planetary roller screw

Abstract

The invention relates to the technical field of mechanical joints, in particular to a full-closed-loop miniature linear electric drive joint based on a reverse planetary roller screw, which comprises a shell assembly, a motor assembly, a reverse roller screw assembly and a drive unit. In order to solve the technical problem that an existing linear actuator has defects, the reverse planetary roller lead screw is utilized, the bearing capacity is greatly improved, and the service life of the whole actuator is prolonged; the connection mode of the motor and the reverse planetary roller screw is improved, the axial size is greatly shortened, and the unit power-to-weight ratio is increased; and the rotary encoder, the linear displacement sensor and the reverse planetary roller screw are highly integrated, so that full-closed-loop control is realized, and the positioning precision is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical joints, and in particular to a full-closed-loop miniature linear electric drive joint based on a reverse planetary roller screw. Background Art

[0002] In the current humanoid robot dexterous hands and new energy battery industries, the life, accuracy and size of linear actuators are increasingly valued. At present, conventional micro linear electric drive joints usually use ball screws or sliding screws. The basic design is that the motor output is fixedly connected to the screw, the screw rotates, and the nut moves linearly. However, the use of ball screws has the defects of small load and low output force; while the use of sliding screws has the defects of large friction and low efficiency.

[0003] In addition, the integration level of existing miniature linear electric-driven joints is not high. For example, the linear encoder at the output end is not integrated with the lead screw, and the motor and the lead screw need to be connected by splines or other means. The low integration level will limit the upper limit of accuracy, making it unsuitable for higher-precision mechanical joints. Summary of the invention

[0004] In response to the technical problems of defects in existing linear actuators, the present invention provides a fully closed-loop miniature linear electric-driven joint based on a reverse planetary roller screw, which utilizes the reverse planetary roller screw to greatly improve the load-bearing capacity and extend the life of the entire actuator; improves the connection method between the motor and the reverse planetary roller screw, greatly shortens the axial dimension, and improves the unit power-to-weight ratio; and highly integrates the rotary encoder and the linear displacement sensor with the reverse planetary roller screw to achieve full closed-loop control and improve positioning accuracy.

[0005] The technical solution provided by the present invention is: a fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw, comprising a housing assembly, a motor assembly, a reverse roller screw assembly and a drive unit; the housing assembly comprises a front end cover, a main housing, a driver housing and a rear end cover, the front end cover and the driver housing are respectively fixed to the two ends of the main housing, and the rear end cover is fixed to one end of the driver housing; the reverse roller screw assembly comprises a nut, a roller and a screw, the screw comprises an engaging section and an executing section, the executing section extends toward the front end cover, and a plurality of rollers surround the outside of the engaging section and engage with the engaging section. , the nut is located on the outside of the roller and meshes with the roller; the motor assembly includes a stator and a rotor, the stator is fixed on the inner side of the main shell, and the rotor is fixed on the outer side of the nut; a sleeve is sleeved on one end of the nut, a magnetic head is arranged on the sleeve, and the drive unit includes a code disk, and the magnetic head and the code disk constitute a rotary encoder; a linear displacement sensor is arranged between the execution section and the front end cover; a ball bearing is fixedly arranged on the outer side of the rear end cover, and a push-pull force sensor is integrated on the ball bearing; the motor assembly, the rotary encoder, the linear displacement sensor and the push-pull force sensor are all electrically connected to the drive unit.

[0006] Optionally, a first lead hole is provided on the front end cover, and the lead wire of the linear displacement sensor passes through the first lead hole; a second lead hole is provided on the driver housing, and the lead wire of the drive unit passes through the second lead hole.

[0007] Optionally, the linear displacement sensor includes a magnetic strip and a sensing unit, wherein the sensing unit is fixed on the front end cover and electrically connected to the driving unit, and the magnetic strip is fixedly arranged along the length direction of the execution section.

[0008] Optionally, the length of the engagement section is less than or equal to 1 / 4 of the length of the magnetic strip.

[0009] Optionally, the length of the magnetic strip is greater than or equal to 85% of the length of the execution segment.

[0010] Optionally, the length of the engagement section is less than or equal to 1 / 5 of the length of the internal thread of the nut.

[0011] Optionally, the length of the engagement segment is less than or equal to 1 / 5 of the length of the execution segment.

[0012] Optionally, a sliding bearing is provided on the front end cover, and at least one inner flat position is provided on the sliding bearing. An outer flat position is correspondingly provided on the execution section, and the outer flat position is abutted and matched with the corresponding inner flat position.

[0013] Optionally, a deep groove ball bearing is provided between the sleeve and the main housing.

[0014] Optionally, a four-point angular contact ball bearing is provided between the sleeve and the main housing.

[0015] Beneficial Effects

[0016] The technical solution provided by the present invention has the following beneficial effects compared with the prior art: in response to the technical problems of defects in existing linear actuators, the fully closed-loop miniature linear electric drive joint based on the reverse planetary roller screw of the present invention utilizes the reverse planetary roller screw to greatly improve the load-bearing capacity and extend the life of the entire actuator; improves the connection method between the motor and the reverse planetary roller screw, greatly shortens the axial size, and improves the unit power-to-weight ratio; and, the rotary encoder and the linear displacement sensor are highly integrated with the reverse planetary roller screw to achieve full closed-loop control and improve positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of a fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw proposed in an embodiment of the present invention.

[0018] Figure 2 It is a schematic cross-sectional view of the structure of a fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings and embodiments.

[0020] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are only used to explain the relevant inventions, rather than to limit the invention. It should also be noted that, for the convenience of description, only the parts related to the invention are shown in the accompanying drawings. The words "first", "second", etc. described in the present invention are set for the convenience of describing the technical solution of the present invention, and have no specific limiting effect. They are all general references and do not constitute a limiting effect on the technical solution of the present invention. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a connection between the insides of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Multiple technical solutions in the same embodiment, and multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions without contradictions or conflicts, all of which are within the scope of protection required by the present invention.

[0021] Example 1

[0022] Combined with Figure 1 and 2 This embodiment proposes a fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw, including a housing assembly, a motor assembly, a reverse roller screw assembly and a drive unit.

[0023] The housing assembly includes a front end cover 21 , a main housing 23 , a driver housing 24 and a rear end cover 22 . The front end cover 21 and the driver housing 24 are respectively fixed to two ends of the main housing 23 , and the rear end cover 22 is fixed to one end of the driver housing 24 .

[0024] The reverse roller screw assembly includes a nut 12, a roller 11 and a screw 10. The screw 10 includes an engaging section 111 and an executing section 112. The executing section 112 extends toward the front end cover 21. A plurality of rollers 11 surround the outside of the engaging section 111 and engage with the engaging section 111. The nut 12 is located on the outside of the roller 11 and engages with the roller 11.

[0025] The motor assembly includes a stator 13 and a rotor 14 . The stator 13 is fixed to the inner side of the main housing 23 , and the rotor 14 is fixed to the outer side of the nut 12 .

[0026] One end of the nut 12 is sleeved with a sleeve 15, on which a magnetic head 16 is arranged, and the drive unit includes a code disk 17, and the magnetic head 16 and the code disk 17 constitute a rotary encoder. A linear displacement sensor is arranged between the execution section 112 and the front end cover 21. A ball bearing 18 is fixedly arranged on the outer side of the rear end cover 22, and a push-pull force sensor is integrated on the ball bearing 18. The motor assembly, the rotary encoder, the linear displacement sensor and the push-pull force sensor are all electrically connected to the drive unit.

[0027] Based on the above structure, the working principle of the fully closed-loop micro linear electric drive joint based on the reverse planetary roller screw of this embodiment is as follows: the reverse planetary roller screw is composed of the nut 12, the roller 11 and the screw 10, the inner side of the nut 12 is processed with threads, the roller 11 is processed with threads and gears, and the meshing section 111 of the screw 10 is processed with threads and gears. The nut 12 is meshed with the roller 11 through threads, and the roller 11 is meshed with the meshing section 111 through threads and gears.

[0028] In the motor assembly, the stator 13 can drive the rotor 14 to drive the nut 12 to rotate. Based on the aforementioned meshing relationship, the rotation of the nut 12 can be converted into the translation of the meshing section 111, so that the execution section 112 can achieve linear motion along with the translation of the meshing section 111. When the joint of this embodiment is used in products such as a robot, the linear motion of the execution section 112 can drive the movement of the finger joints in the robot.

[0029] The movement of the screw rod is controlled by the motor assembly, and the motor is controlled by the drive unit. In this embodiment, the drive unit is arranged in the housing assembly, near the end of the nut 12, that is, in the inner cavity of the driver housing 24.

[0030] The drive unit includes relevant hardware circuits and motor drive control circuits, and also includes a code disk 17. The end of the nut 12 is sleeved with a sleeve 15, that is, the sleeve 15 is fixed to the outside of the nut 12, and the sleeve 15 can rotate with the rotation of the nut 12. A magnetic head 16 is fixed on the sleeve 15, and the magnetic head 16 faces the code disk 17. Therefore, as the sleeve 15 rotates, the magnetic head 16 rotates accordingly, and the code disk 17 senses the rotation of the magnetic head 16, and the rotary encoder can read the rotating electrical signal.

[0031] Furthermore, a linear displacement sensor is provided between the execution section 112 and the front end cover 21, which can read the linear displacement of the execution section 112. In addition, a ball bearing 18 is fixedly provided on the outer side of the rear end cover 22 for connection with an external mechanism, such as assembly with a component of the manipulator, and the ball bearing 18 can also offset most of the non-axial forces received during operation. A push-pull force sensor is integrated on the ball bearing 18, which can collect push-pull force electrical signals.

[0032] Based on the setting of the rotary encoder, the linear displacement sensor and the push-pull force sensor, the drive unit can output the motor assembly in combination with the electrical signals collected by these sensors, thereby changing the motion condition of the rotor 14 and further changing the motion condition of the lead screw 10.

[0033] In a preferred embodiment, the front cover 21 is provided with a first lead hole, and the lead wire of the linear displacement sensor passes through the first lead hole; the driver housing 24 is provided with a second lead hole, and the lead wire of the drive unit passes through the second lead hole. In this embodiment, by reserving the first lead hole and the second lead hole, it is convenient to connect the internal circuit of the housing component with the outside world.

[0034] In another preferred embodiment, the linear displacement sensor includes a magnetic strip 25 and a sensing unit 26, wherein the sensing unit 26 is fixed to the front end cover 21 and electrically connected to the driving unit, and the magnetic strip 25 is fixedly arranged along the length direction of the execution section 112. In this embodiment, the position signal of the execution section 112 during the linear motion process can be read more accurately, and the integration of the linear displacement sensor is further realized.

[0035] In a further embodiment, the length of the engagement section 111 is less than or equal to 1 / 4 of the length of the magnetic strip 25. The length of the magnetic strip 25 can be regarded as the effective telescopic length of the lead screw 10. The purpose of this embodiment is to reduce the proportion of the engagement section 111 to the effective stroke of the lead screw 10, so that the execution section 112 has a wider motion stroke.

[0036] And, in an improved embodiment, the length of the magnetic stripe 25 is greater than or equal to 85% of the length of the execution section 112. Combined with the above description, the length of the magnetic stripe 25 can be substantially equivalent to the output effective length of the execution section 112, so the output effective length should be as long as possible, that is, the length of the magnetic stripe 25 is preferably greater than or equal to 85% of the length of the execution section 112.

[0037] In other embodiments, the length of the meshing section 111 is less than or equal to 1 / 5 of the length of the internal thread of the nut 12. The purpose of this embodiment is to reduce the proportion of the meshing area, so that the execution section 112 of the screw 10 has as large a movable stroke as possible, improve the overall use efficiency, and reduce the overall volume to a certain extent.

[0038] In an improved embodiment similar to the above embodiment, the length of the engagement section 111 is less than or equal to 1 / 5 of the length of the execution section 112. The purpose is also to achieve a larger stroke movement of the execution section 112 through a smaller engagement area, thereby improving the overall use efficiency.

[0039] In other embodiments, a sliding bearing 27 is provided on the front end cover 21, and at least one inner flat position is provided on the sliding bearing 27, and an outer flat position is correspondingly provided on the execution section 112, and the outer flat position abuts and cooperates with the corresponding inner flat position. In this embodiment, the execution section 112 has one or four or other number of outer flat positions, and the sliding bearing 27 is provided with a corresponding inner flat position, and the inner flat position cooperates with the outer flat position to achieve an anti-rotation function. The provision of the sliding bearing 27 can reduce the wear between the execution section 112 of the lead screw 10 and the front end cover 21.

[0040] And, in order to ensure the smoothness and stability of the rotation of the nut 12, a deep groove ball bearing 28 can be provided between the sleeve 15 and the main housing 23. Similarly, a four-point angular contact ball bearing 29 can also be provided between the sleeve 15 and the main housing 23 to bear axial and radial loads.

[0041] To sum up, in response to the technical problems of defects in existing linear actuators, the fully closed-loop miniature linear electric-driven joint based on the reverse planetary roller screw of this embodiment utilizes the reverse planetary roller screw to greatly improve the load-bearing capacity and extend the life of the entire actuator; improves the connection method between the motor and the reverse planetary roller screw, greatly shortens the axial dimension, and improves the unit power-to-weight ratio; and, highly integrates the rotary encoder and the linear displacement sensor with the reverse planetary roller screw to achieve full closed-loop control and improve positioning accuracy.

[0042] The present invention and its embodiments are described schematically above, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and creatively designs a structure and an embodiment similar to the technical solution without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw, characterized in that: It includes a housing assembly, a motor assembly, a reverse roller screw assembly and a drive unit; The housing assembly comprises a front end cover (21), a main housing (23), a driver housing (24) and a rear end cover (22); the front end cover (21) and the driver housing (24) are respectively fixed to two ends of the main housing (23), and the rear end cover (22) is fixed to one end of the driver housing (24); The reverse roller screw assembly comprises a nut (12), a roller (11) and a screw (10); the screw (10) comprises an engagement section (111) and an execution section (112); the execution section (112) extends toward the front end cover (21); a plurality of rollers (11) surround the outside of the engagement section (111) and are engaged with the engagement section (111); and the nut (12) is located outside the roller (11) and is engaged with the roller (11); The motor assembly comprises a stator (13) and a rotor (14), wherein the stator (13) is fixed to the inner side of the main housing (23), and the rotor (14) is fixed to the outer side of the nut (12); One end of the nut (12) is sleeved with a sleeve (15), and a magnetic head (16) is arranged on the sleeve (15); the drive unit includes a code disk (17), and the magnetic head (16) and the code disk (17) constitute a rotary encoder; a linear displacement sensor is arranged between the execution section (112) and the front end cover (21); a ball bearing (18) is fixedly arranged on the outer side of the rear end cover (22), and a push-pull force sensor is integrated on the ball bearing (18); the motor assembly, the rotary encoder, the linear displacement sensor and the push-pull force sensor are all electrically connected to the drive unit.

2. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 1, characterized in that: The front end cover (21) is provided with a first lead hole, and the lead wire of the linear displacement sensor passes through the first lead hole; the driver housing (24) is provided with a second lead hole, and the lead wire of the drive unit passes through the second lead hole.

3. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 1, characterized in that: The linear displacement sensor comprises a magnetic strip (25) and a sensing unit (26); the sensing unit (26) is fixed on the front end cover (21) and electrically connected to the driving unit; the magnetic strip (25) is fixedly arranged along the length direction of the execution section (112).

4. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 3, characterized in that: The length of the engagement section (111) is less than or equal to 1 / 4 of the length of the magnetic strip (25).

5. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 3, characterized in that: The length of the magnetic strip (25) is greater than or equal to 85% of the length of the execution section (112).

6. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 1 or 4, characterized in that: The length of the meshing section (111) is less than or equal to 1 / 5 of the length of the internal thread of the nut (12).

7. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 1 or 4, characterized in that: The length of the engagement section (111) is less than or equal to 1 / 5 of the length of the execution section (112).

8. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 1, characterized in that: The front end cover (21) is provided with a sliding bearing (27), the sliding bearing (27) is provided with at least one inner flat position, and the execution section (112) is correspondingly provided with an outer flat position, the outer flat position abuttingly engaging with the corresponding inner flat position.

9. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 1, characterized in that: A deep groove ball bearing (28) is provided between the sleeve (15) and the main housing (23).

10. A fully closed-loop miniature linear electric drive joint based on a reverse planetary roller screw according to claim 1 or 9, characterized in that: A four-point angular contact ball bearing (29) is arranged between the sleeve (15) and the main housing (23).

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