Linear driving mechanism

Abstract

Provided in the present invention is a linear driving mechanism, which comprises a housing with two ends open, a front cover and a rear cover which are fixed to the two opposite ends of the housing respectively, a stator arranged in the housing, and a hollow rotor which is arranged in the stator and is rotationally connected to the stator; a ball screw comprises a lead screw nut fixed in the rotor and a central lead screw arranged on the inner circumferential side of the lead screw nut; first ball grooves which are spiral in shape are provided at intervals in the inner circumferential side of the lead screw nut, and second ball grooves which are spiral in shape are provided in the outer circumferential side of the central lead screw; the ball screw further comprises a plurality of balls, the plurality of balls being clamped between the first ball grooves and the second ball grooves, so that a rolling connection is formed between the lead screw nut and a lead screw body. The linear driving mechanism of the present invention can achieve real-time control, has good reliability and high efficiency, exhibits more balanced drive force, has a low height and short length overall, and involves installation-friendly dimensions and a simple structure.

Description

Linear driving mechanism TECHNICAL FIELD

[0001] The present application relates to the technical field of linear driving, in particular to a linear driving mechanism. BACKGROUND

[0002] At present, humanoid robots are a kind of automation machines which can assist or even replace human beings to complete dangerous, heavy and complex work. The fingers of humanoid robots are important parts for realizing actions and completing tasks, but due to the limitations of space and energy saving, more stringent requirements are needed for the linear actuators of the fingers, that is, the linear actuators need to develop in the direction of high integration, small size, high bearing capacity and fast response.

[0003] In the related art, the linear actuator mainly adopts a brush motor and a multi-stage planetary reducer structure. In this linear actuator, the force transmission of the brush motor will have obvious hysteresis phenomenon after multi-stage reduction, the real-time control performance is poor, and the efficiency decreases rapidly with the increase of the number of stages after multi-stage transmission. At the same time, the brush motor itself also has the problems of poor reliability of the brush, unbalanced three-phase resistance and torque due to contact problems.

[0004] In summary, the linear actuator in the related art has the problems of poor real-time control performance and reliability, low efficiency, and unbalanced driving force.

[0005] Therefore, it is necessary to provide a new linear driving mechanism to solve the above technical problems. TECHNICAL PROBLEM

[0006] The purpose of the present application is to provide a linear driving mechanism, which aims to solve the problems of poor real-time control performance and reliability, low efficiency, and unbalanced driving force of the linear actuator in the related art. TECHNICAL SOLUTION

[0007] In order to achieve the above purpose, the present application provides a linear driving mechanism, which comprises a shell with two open ends, a front cover and a rear cover fixed respectively at opposite ends of the shell, a stator arranged in the shell, and a rotor arranged in the stator and forming a rotating connection with the stator and being hollow; the linear driving mechanism further comprises a ball screw sleeved in the rotor;

[0008] The ball screw comprises a screw nut fixed in the rotor and being hollow, and a central screw arranged on the inner circumferential side of the screw nut and penetrating the front cover, and the screw nut forms a rotating connection with the shell and the central screw respectively;

[0009] The inner circumferential side of the screw nut is provided with a first ball groove which is inwardly recessed and thread-like, and the outer circumferential side of the central screw rod is provided with a second ball groove which is inwardly recessed and thread-like and is correspondingly provided with the first ball groove; the ball screw further comprises a plurality of balls, and the plurality of balls are clamped between the first ball groove and the second ball groove to form a rolling connection between the screw nut and the central screw rod.

[0010] Preferably, the stator comprises a stator core fixed to the side of the shell close to the rotor and a coil winding fixed in the stator core, the coil winding is spaced apart from the rotor, the coil winding is formed by a plurality of coils laminated and bonded and is annular, and the coil winding drives the rotor to rotate after being energized;

[0011] The stator drives the rotor to rotate to drive the screw nut to rotate, so that the screw nut rotates to drive the central screw rod to realize linear extension and retraction.

[0012] Preferably, the stator core is an annular magnetic steel sleeve; or,

[0013] The stator core is formed by laminating a plurality of silicon steel sheets by bonding or riveting.

[0014] Preferably, the stator core is a toothless core.

[0015] Preferably, the rotor is a magnetic hollow shaft structure, and the permanent magnet installed on the magnetic hollow shaft structure is a radial 4-pole or 6-pole magnetic ring structure.

[0016] Preferably, the rotor is a magnetic hollow shaft structure, and the permanent magnet installed on the magnetic hollow shaft structure is a magnetic sheet structure, which is pasted on the magnetic hollow shaft structure to form a radial 4-pole or 6-pole magnetic field.

[0017] Preferably, the rotor is made of a neodymium iron boron material with a performance grade greater than or equal to N45H.

[0018] Preferably, the central screw rod comprises a screw rod body provided in the screw nut and an extension end protruding and extending from one end of the screw rod body close to the front cover and penetrating through the front cover.

[0019] Preferably, the linear drive mechanism further comprises a control panel fixed to the shell and the front cover respectively and spaced apart from the stator, a linear position sensor electrically connected to the control panel, and a rectangular stopper fixed to the extension end and abutting against the screw rod body; the linear position sensor is used to collect linear movement data of the stopper.

[0020] Preferably, the linear position sensor comprises a linear sensing magnet fixed to the stopper near the control plate, and a first Hall sensor fixed to the control plate near the center screw and within the magnetic field of the linear sensing magnet; or,

[0021] The linear position sensor comprises a spring sheet arranged on the stopper near the control plate, and a conductor resistor in the shape of a long strip fixed to the control plate near the center screw; the spring sheet slides on the surface of the conductor resistor along with the stopper, and the linear extension length of the extension end is collected by the difference of the conductor resistor at different positions.

[0022] Preferably, the linear driving mechanism further comprises a control plate and an angle position sensor for collecting the angle information of the motor composed of the stator and the rotor; the control plate is fixed to the machine shell and the front cover respectively and is arranged in the control plate spaced from the stator, and the angle position sensor comprises a second Hall sensor fixed to the control plate and within the magnetic field of the rotor; the second Hall sensor is used to collect the angle information of the motor composed of the stator and the rotor.

[0023] Preferably, the linear driving mechanism further comprises an angle position sensor for collecting the angle information of the motor composed of the stator and the rotor; the angle position sensor comprises a collecting part fixed to the rear cover near the screw nut and a rotating part fixed to the screw nut near the rear cover, and the rotating part is arranged opposite to and spaced from the rotating part.

[0024] Preferably, the Hall sensor chip of the angle position sensor has two, and the two Hall sensor chips are respectively located at one end of the control plate away from the linear driving mechanism and in the radial direction of the rotor, and the angle position of the rotor is identified by sensing the angle phase signal of the rotor magnet magnetic field.

[0025] Preferably, the end of the rotor is provided with a brake device for providing a locked-rotor torque when the motor composed of the stator and the rotor needs to be locked.

[0026] Preferably, the machine shell has an open structure at both ends, and the machine shell, the front cover and the rear cover are connected into one body by bolts.

[0027] Preferably, the machine shell comprises a front section machine shell and a rear section machine shell, the rear section machine shell is integrated into the rear cover, and the front cover, the front section machine shell and the rear cover integrated with the rear section machine shell are connected into one body by bolts. Advantages

[0028] Compared with the prior art, the linear drive mechanism of the present invention realizes linear drive by adopting a motor consisting of a stator and a rotor in combination with a ball screw, and the ball screw is limited to include a hollow screw nut fixed in the rotor, a center screw arranged on the inner circumference of the screw nut and passing through the front cover, and a plurality of balls. The plurality of balls are clamped between the first ball groove and the second ball groove so that the screw nut and the center screw form a rolling connection. This design method can realize real-time control of the linear drive mechanism, and has good reliability, high efficiency, and more balanced driving force. In addition, it can also make the overall height of the linear drive mechanism low, the length small, the installation size friendly, and the structure simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0030] FIG1 is a schematic diagram of the three-dimensional structure of a linear drive mechanism provided in Example 1 of the present invention;

[0031] FIG2 is an exploded perspective view of the linear drive mechanism according to the first embodiment of the present invention;

[0032] FIG3 is a cross-sectional view taken along line AA of FIG1 ;

[0033] FIG4 is a schematic diagram of the three-dimensional structure of a linear drive mechanism provided in Embodiment 2 of the present invention;

[0034] FIG5 is a cross-sectional view taken along line BB of FIG4 ;

[0035] FIG6 is a schematic diagram of the three-dimensional structure of the linear drive mechanism provided in Example 3 of the present invention;

[0036] FIG7 is a cross-sectional view taken along line CC of FIG6 .

[0037] In the figure, 100, linear drive mechanism, 1, housing, 2, front cover, 3, rear cover, 4, stator, 41, stator core, 42, coil winding, 5, rotor, 6, ball screw, 61, screw nut, 611, first ball groove, 62, center screw, 621, screw body, 622, second ball groove, 623, protruding end, 63, ball; 7, control board, 8, linear position sensor, 81, linear sensor magnet, 82, first Hall sensor, 83, spring piece, 84, conductor resistor, 9, stop block, 91, groove, 10, angular position sensor, 101, second Hall sensor, 102, collecting part, 103, rotating part, 104, magnet seat, 11, first bearing, 12, second bearing. Embodiments of the present application

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0039] Embodiment one

[0040] The linear driving mechanism 100 provided by the embodiments of the present application comprises a shell 1 with two open ends, a front cover 2 and a rear cover 3 fixed to opposite ends of the shell 1 respectively, a stator 4 arranged in the shell 1, and a rotor 5 arranged in the stator 4 and in hollow connection with the stator 4.

[0041] The shell 1 is in a two-end-open structure, and the shell 1, the front cover 2 and the rear cover 3 are connected into one body by bolts.

[0042] The shell 1 comprises a front shell and a rear shell, and circular holes are arranged at four corner positions of the front shell and the rear shell and are fixed by long bolts in series. Of course, according to actual requirements, the rear shell can be fused into the rear cover 3 as one body, and the front cover 2, the front shell, and the rear cover 3 with the fused rear shell are connected into one body by bolts; or the front shell can be fused into the front cover 2 as one body, and the front cover 2 with the fused front shell, the rear shell and the rear cover 3 are connected into one body by bolts.

[0043] The stator 4 comprises a stator core 41 fixed to one side of the shell 1 close to the rotor 5 and a coil winding 42 fixed in the stator core 41, the coil winding 42 is arranged in space with the rotor 5, the coil winding 42 is formed by stacking and bonding of multiple coils and is in a circular ring shape, and the coil winding 42 drives the rotor 5 to rotate after being electrified. In the embodiment, the coil winding 42 is formed by stacking and bonding of six coils and is in a circular ring shape, that is, the coil winding 42 is in a hollow structure.

[0044] The stator core 41 is a ring-shaped magnetic steel sleeve; or the stator core 41 is formed by stacking of multiple silicon steel sheets by bonding or riveting; and the stator core 31 is a toothless core.

[0045] The rotor 5 is a magnetic hollow shaft structure. The permanent magnet arranged on the magnetic hollow shaft structure is a magnetic ring structure with radial 4 poles or 6 poles; or the permanent magnet arranged on the magnetic hollow shaft structure is a magnetic sheet structure, which is pasted on the magnetic hollow shaft structure to form a radial 4-pole or 6-pole magnetic field.

[0046] The end of the rotor 5 (a magnetically conductive hollow shaft structure) is provided with a brake device for providing a locked-rotor torque when the motor formed by the stator 4 and the rotor 5 needs to be locked, so as to avoid temperature rise caused by long-term locked-rotor of the motor, and also to reduce the energy consumption of the motor.

[0047] The rotor 5 is made of a neodymium-iron-boron material with a performance grade greater than or equal to N45H.

[0048] Specifically, the linear driving mechanism 100 further comprises a ball screw 6 sleeved in the rotor 5.

[0049] The ball screw 6 comprises a hollow screw nut 61 fixed in the rotor 5 and a central screw rod 62 provided on the inner circumferential side of the screw nut 61 and penetrating the front cover 2, and the screw nut 61 is rotationally connected with the casing 1 and the central screw rod 62, respectively.

[0050] The inner circumferential side of the screw nut 61 is provided with a first ball groove 611 recessed inward and in a threaded spiral, and the outer circumferential side of the central screw rod 62 is provided with a second ball groove 622 recessed inward and in a threaded spiral, which is correspondingly arranged with the first ball groove 611; the ball screw 6 further comprises a plurality of balls 63 clamped between the first ball groove 611 and the second ball groove 622 to form a rolling connection between the screw nut 61 and the central screw rod 62.

[0051] The stator 4 drives the rotor 5 to rotate to rotate the screw nut 61, so that the screw nut 61 rotates to drive the central screw rod 62 to realize linear extension and retraction.

[0052] The central screw rod 62 comprises a screw body 621 provided in the screw nut 61 and an extension end 623 protruding and extending from one end of the screw body 621 close to the front cover 2 and penetrating the front cover 2; the second ball groove 622 is provided on the outer circumferential side of the screw body 621.

[0053] Specifically, the linear driving mechanism 100 further comprises a control board 7 fixed to the casing 1 and the front cover 2, respectively, and spaced apart from the stator 4, a linear position sensor 8 electrically connected with the control board 7, and a rectangular stop block 9 sleeved and fixed to the extension end 623 and abutting against the screw body 621; the linear position sensor 8 is used to collect linear movement data of the stop block 9.

[0054] The end of the casing 1 close to the front cover 2 is provided with a recessed groove, and the control board 7 located at the cover is inserted into the groove.

[0055] The linear position sensor 8 comprises a linear sensor magnet 81 fixed to the block 9 near the side of the control plate 7 and a first Hall sensor 82 fixed to the control plate 7 near the side of the lead screw 62 and located in the magnetic field range of the linear sensor magnet 81; the linear sensor magnet 81 comprises one or more. In the embodiment, the linear sensor magnet 81 comprises three and is arranged at intervals; the block 9 near the side of the control plate 7 is provided with an inwardly recessed groove 91, and the linear sensor magnet 81 is installed in the groove 91. Of course, according to actual needs, the linear sensor magnet 81 can also be directly pasted on the extension end 623 and located at the original position of the block 9 to save cost.

[0056] Specifically, the linear driving mechanism 100 further comprises an angle position sensor 10 for collecting angle information of the motor composed of the stator 4 and the rotor 5; the angle position sensor 10 comprises a second Hall sensor 101 fixed to the control plate 7 and located in the magnetic field range of the rotor 5; the second Hall sensor 101 is used to collect the angle information of the motor composed of the stator 4 and the rotor 5; the linear sensor magnet 81 comprises one or more. In the embodiment, the linear sensor magnet 81 comprises one.

[0057] Specifically, the linear driving mechanism 100 further comprises a first bearing 11 and a second bearing 12; the first bearing 11 and the second bearing 12 are respectively sleeved and fixed to the two ends of the screw nut 61, and the outer periphery of the first bearing 11 and the outer periphery of the second bearing 12 are respectively fixed in the shell 1; the second bearing 12 is near the rear cover 3.

[0058] Wherein, the second Hall sensor 101 is located above the area between the stator 4 and the second bearing 12.

[0059] The linear driving mechanism 100 in the embodiment is applied to the dexterous fingers or joints of the robot.

[0060] The linear driving mechanism 100 of the embodiment is driven linearly by the motor composed of the stator 4 and the rotor 5 and the ball screw 6, and the limiting ball screw 6 includes the screw nut 61 fixed in the rotor 5 and hollow, the central screw rod 62 arranged on the inner circumferential side of the screw nut 61 and penetrating the front cover 2, and the plurality of balls 63, the plurality of balls 63 being clamped between the first ball groove 611 and the second ball groove 622 to form rolling connection between the screw nut 61 and the screw rod body 621. This design can realize real-time control of the linear driving mechanism 100, has good reliability, high efficiency, more balanced driving force, and can also make the overall height of the linear driving mechanism 100 low, the length small, the installation size friendly, and the structure simple. The stator 4 is designed as a toothless slot structure, i.e. the motor composed of the stator 4 and the rotor 5 has no toothed slot torque, so that the motor has small jitter in speed regulation, the motor driving force is stable, the thrust is stable in the required driving length range, the fluctuation is small, the driving control is simple, and the rotor 5 is a magnetic ring structure of a permanent magnet, which has simple structure, no brush friction, and faster dynamic response.

[0061] Embodiment Two

[0062] In combination with FIGS. 4 to 5, the first difference between the embodiment and the embodiment one is that the linear position sensor 8 includes the elastic sheet 83 arranged on the side of the stop block 9 close to the control panel 7 and the conductor resistor 84 fixed on the side of the control panel 7 close to the central screw rod 62 and in a long strip shape; the elastic sheet 83 slides on the surface of the conductor resistor 84 with the stop block 9, and the linear extension length of the extension end 623 is collected by the difference of the conductor resistor 84 at different positions.

[0063] The second difference between the embodiment and the embodiment one is that the angle position sensor 10 includes the collection part 102 fixed on the side of the rear cover 3 close to the screw nut 61 and the rotating part 103 fixed on the side of the screw nut 61 close to the rear cover 3, and the rotating part 103 is arranged opposite to the rotating part 103 and spaced apart.

[0064] The collection part 102 includes the collection plate fixed on the rear cover 3 and the sensor fixed on the collection plate; the rotating part 103 includes the magnet seat 104 fixed on the screw nut 61 and the angle sensor magnet (permanent magnet) fixed on the side of the magnet seat 104 close to the rear cover 3.

[0065] Embodiment Three

[0066] In combination with FIGS. 6 to 7, the difference between the embodiment and the embodiment one is that the angle position sensor 10 includes the collection part 102 fixed on the side of the rear cover 3 close to the screw nut 61 and the rotating part 103 fixed on the side of the screw nut 61 close to the rear cover 3, and the rotating part 103 is arranged opposite to the rotating part 103 and spaced apart.

[0067] The collecting part 102 comprises a collecting plate fixed to the back cover 3 and a sensor fixed to the collecting plate; the rotating part 103 comprises a magnet base 104 fixed to the screw nut 61 and an angle sensor magnet (permanent magnet) fixed to the magnet base 104 close to the back cover 3.

[0068] In the embodiment, the Hall sensor chip of the angle position sensor 10 has two, which are respectively located at one end of the control plate 7 away from the linear driving mechanism 100 and in the radial direction of the rotor 5, and the angle position of the rotor 5 is recognized by sensing the angle phase signal of the magnet field of the rotor 5.

[0069] The above only describes the embodiments of the present application, and it should be pointed out that, for those skilled in the art, improvements can be made without departing from the inventive concept, but these all belong to the protection scope of the present application.

Claims

1. A linear drive mechanism comprising a housing with openings at both ends, a front cover and a rear cover fixed to opposite ends of the housing, a stator disposed within the housing, and a hollow rotor disposed within and rotatably connected to the stator; characterized in that: The linear drive mechanism further includes a ball screw sleeved inside the rotor; The ball screw includes a hollow screw nut fixed in the rotor and a central screw arranged on the inner circumference of the screw nut and passing through the front cover, wherein the screw nut is rotationally connected to the housing and the central screw respectively; The inner circumference of the screw nut is provided with first ball grooves that are inwardly concave and have a threaded shape, and the outer circumference of the center screw is provided with second ball grooves that are inwardly concave and have a threaded shape and are respectively arranged corresponding to the first ball grooves; the ball screw further includes a plurality of balls, and the plurality of balls are sandwiched between the first ball grooves and the second ball grooves so that the screw nut and the center screw form a rolling connection; The stator drives the rotor to rotate to drive the lead screw nut to rotate, so that the lead screw nut rotates to drive the central lead screw to realize linear telescopic motion.

2. The linear drive mechanism according to claim 1, wherein: The stator includes a stator core fixed to the side of the housing close to the rotor and a coil winding fixed in the stator core. The coil winding is spaced apart from the rotor. The coil winding is formed by stacking and bonding multiple coils and is in a circular ring shape. When the coil winding is energized, it drives the rotor to rotate.

3. The linear drive mechanism according to claim 2, wherein: The stator core is an annular magnetic steel sleeve; or, The stator core is formed by stacking multiple silicon steel sheets by bonding or riveting.

4. The linear drive mechanism according to claim 3, wherein: The stator core is a slotless core.

5. The linear drive mechanism according to claim 1, wherein: The rotor is a magnetic hollow shaft structure, and the permanent magnet mounted on the magnetic hollow shaft structure is a radial 4-pole or 6-pole magnetic ring structure.

6. The linear drive mechanism according to claim 1, wherein: The rotor is a magnetic hollow shaft structure, and the permanent magnet mounted on the magnetic hollow shaft structure is a magnetic sheet structure. The magnetic sheet structure is adhered to the magnetic hollow shaft structure to form a radial 4-pole or 6-pole magnetic field.

7. The linear drive mechanism according to claim 1, wherein: The rotor is made of neodymium iron boron material with a performance grade greater than or equal to N45H.

8. The linear drive mechanism according to claim 1, wherein: The central screw includes a screw body arranged in the screw nut and an extended end formed by protruding and extending from one end of the screw body close to the front cover and passing through the front cover; the second ball groove is arranged on the outer peripheral side of the screw body.

9. The linear drive mechanism according to claim 8, characterized in that: The linear drive mechanism also includes a control board respectively fixed to the housing and the front cover and spaced apart from the stator, a linear position sensor electrically connected to the control board, and a rectangular block that is sleeved and fixed on the protruding end and abuts against the screw body; the linear position sensor is used to collect linear movement data of the block.

10. The linear drive mechanism according to claim 9, characterized in that: The linear position sensor includes a linear sensor magnet fixed to the side of the stopper close to the control board and a first Hall sensor fixed to the side of the control board close to the central screw and located within the magnetic field range of the linear sensor magnet; or The linear position sensor includes a spring piece arranged on the side of the block close to the control board and a long strip-shaped conductor resistor fixed to the side of the control board close to the center screw rod; the spring piece slides on the surface of the conductor resistor along with the block, and the linear extension length of the extension end is collected through the difference in conductor resistance at different positions.

11. The linear drive mechanism according to claim 1, wherein: The linear drive mechanism also includes a control board and an angular position sensor, wherein the angular position sensor is used to collect angular information of the motor composed of the stator and the rotor; the control board is respectively fixed to the housing and the front cover and is spaced apart from the stator, and the angular position sensor includes a second Hall sensor fixed to the control board and located within the magnetic field range of the rotor; the second Hall sensor is used to collect angular information of the motor composed of the stator and the rotor.

12. The linear drive mechanism according to claim 9, wherein: The linear drive mechanism also includes an angular position sensor, which is used to collect angular information of the motor composed of the stator and the rotor; the angular position sensor includes a collecting part fixed to the side of the rear cover close to the screw nut and a rotating part fixed to the side of the screw nut close to the rear cover, and the rotating part is opposite to the rotating part and is arranged at a distance.

13. The linear drive mechanism according to claim 12, wherein: The angular position sensor has two Hall sensor chips, which are respectively located at one end of the control board away from the linear drive mechanism and in the radial direction of the rotor. The angular position of the rotor is identified by sensing the angular phase signal of the rotor magnet magnetic field.

14. The linear drive mechanism according to claim 1, wherein: A brake device is provided at the end of the rotor for providing a stall torque when the motor composed of the stator and the rotor needs to be stalled.

15. The linear drive mechanism according to claim 1, wherein: The housing is a structure with openings at both ends, and the housing, the front cover and the rear cover are connected as a whole by bolts.

16. The linear drive mechanism according to claim 1, wherein: The housing includes a front housing and a rear housing, the rear housing is integrated into the rear cover, and the front cover, the front housing, and the rear cover integrated with the rear housing are connected into a whole using bolts.

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