Linear actuating mechanism

Abstract

The present invention provides a linear actuating mechanism, comprising a casing, a front cover and a rear cover which are respectively fixed at two opposite ends of the casing, a stator disposed in the casing, and a hollow rotor disposed in the stator, wherein the stator drives the rotor to rotate. The linear actuating mechanism further comprises a ball screw sleeved in the rotor, a first bearing sleeved on the rotor and fixed at one end of the rear cover, and a second bearing sleeved on the ball screw and fixed in the casing; the ball screw comprises a central screw disposed on the inner peripheral side of the rotor and a screw nut sleeved on the central screw; the screw nut is formed on the inner peripheral side of the end of the rotor close to the front cover. The linear actuating mechanism of the present invention can improve the degree of integration of the ball screw and the rotor, thereby reducing the volume space of the linear actuating mechanism and satisfying the miniaturization requirement.

Description

Linear drive mechanism Technical Field

[0001] The present invention relates to the field of linear drive technology, and in particular to a linear drive mechanism. Background Art

[0002] The current artificial intelligence and robotics industries are experiencing rapid growth. Due to high space and energy efficiency requirements, linear actuators are facing stricter restrictions. Consequently, linear actuators are developing towards high integration, miniaturization, high load capacity, and fast response. A linear drive mechanism is a type of linear actuator. It primarily uses a central lead screw as the active element and a nut as the linear output, meaning the lead screw and nut move telescopically along their axis.

[0003] Most standard linear screw drive mechanisms use coaxial motors connected to the rotating shaft via gears or couplings to push the nut to move forward or backward axially.

[0004] In addition to the motor, the above-mentioned linear screw drive mechanism mainly includes a center screw and a screw nut rotatably connected to the center screw, that is, the center screw rotates to push the screw nut to perform linear motion. The center screw and screw nut in the related technology are both separate structures and are not integrated with other components. This leads to a low degree of integration of the linear screw drive mechanism, greatly increases the volume space of the overall structure, and cannot meet the needs of miniaturization.

[0005] Therefore, it is necessary to provide a new linear drive mechanism to solve the above technical problems. Technical issues

[0006] The purpose of the present invention is to provide a linear drive mechanism to solve the problem that the linear drive mechanism in the related art has low integration, resulting in a large volume space of the overall structure and cannot meet the miniaturization requirements. Technical Solutions

[0007] To achieve the above-mentioned object, the present invention provides a linear drive mechanism comprising a housing, a front cover and a rear cover respectively fixed to opposite ends of the housing, a stator disposed within the housing, and a hollow rotor disposed within the stator, wherein the stator drives the rotor to rotate; the linear drive mechanism further comprises a rolling screw sleeved within the rotor, a first bearing sleeved on the rotor and fixed to one end of the rear cover, and a second bearing sleeved on the rolling screw and fixed within the housing;

[0008] The rolling screw includes a center screw arranged on the inner circumference of the rotor and passing through the front cover, and a screw nut sleeved on the center screw and rotatingly connected to the center screw; the screw nut is fixed in the second bearing, and the screw nut is formed on the inner circumference of one end of the rotor close to the front cover. The rotation of the rotor drives the screw nut to rotate, so that the rotation of the screw nut drives the center screw to realize linear telescopic motion.

[0009] Preferably, the rolling screw is a planetary roller screw, and the screw nut is provided with an internal thread structure on the side close to the center screw; the center screw includes a screw body arranged on the inner circumference of the rotor and an extension formed by extending from one end of the screw body close to the front cover, and the outer circumference of the screw body is provided with an external thread structure; the screw nut is engaged with the external thread structure of the screw body through the internal thread structure to achieve a rotational connection.

[0010] Preferably, the rolling screw also includes a first gear ring and a second gear ring respectively fixed at both ends of the screw nut and a plurality of annular screw columns arranged at intervals around the central screw, and the outer peripheral side of each of the annular screw columns is respectively provided with a screw column external thread structure; the two ends of each of the annular screw columns are respectively arranged on the first gear ring and the second gear ring and form a rotational connection, the screw column external thread structure of each of the annular screw columns is respectively engaged with the external thread structure of the screw body, and the screw column external thread structure of each of the annular screw columns is also respectively engaged with the internal thread structure of the screw nut.

[0011] Preferably, the rolling screw is a ball screw, and a plurality of first ball grooves in the form of a threaded depression are provided at intervals on one side of the screw nut close to the center screw; the center screw includes a screw body provided on the rotor and an extension formed by extending from one end of the screw body close to the front cover, and a plurality of second ball grooves in the form of a threaded depression are provided at intervals on the outer peripheral side of the screw body; the rolling screw also includes a plurality of balls, each of the balls being clamped between one of the first ball grooves and one of the second ball grooves so that the screw nut forms a rolling connection with the screw body.

[0012] Preferably, the inner side of one end of the rotor close to the front cover protrudes and extends along its radial direction to form a protrusion; the screw nut is formed on the inner circumference side of the protrusion close to the center screw.

[0013] Preferably, the first bearing and the second bearing are respectively located on opposite sides of the stator and spaced apart from the stator; the outer wall of the rotor protrudes to form a shaft stop, the end of the second bearing close to the front cover abuts against the front cover, and the end of the second bearing away from the front cover abuts against the shaft stop.

[0014] Preferably, the length of the screw nut is 1 / 8-3 / 4 of the length of the rotor.

[0015] Preferably, the rotor includes a hollow rotating shaft disposed in the casing and a plurality of permanent magnets spaced around the rotating shaft and fixed to the outer wall of the rotating shaft; the plurality of permanent magnets are spaced apart from the stator, the first bearing and the second bearing are respectively sleeved on the rotating shaft, and the screw nut is formed on the inner circumference of one end of the rotating shaft close to the front cover.

[0016] Preferably, the motor formed by the stator and the rotor together has an 8-pole 9-slot structure, a 10-pole 12-slot structure, a 14-pole 12-slot structure, a 14-pole 15-slot structure, a 16-pole 15-slot structure, or a 16-pole 18-slot structure.

[0017] Preferably, the linear drive mechanism further includes a position sensor; the position sensor includes a collecting part fixed to the rear cover and a rotating part fixed to one end of the rotor close to the rear cover, and the collecting part is opposite to the rotating part and is spaced apart. Beneficial effects

[0018] Compared with the prior art, the linear drive mechanism of the present invention forms the screw nut of the rolling screw on the inner circumference of one end of the rotor close to the front cover. This not only improves the integration of the rolling screw and the rotor, thereby reducing the volume space of the linear drive mechanism and meeting the needs of miniaturization, but also improves the bearing capacity of the rolling screw. At the same time, since the screw nut is not completely formed along the entire length of the rotor, this can also reduce the difficulty of processing the screw nut. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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:

[0020] FIG1 is a schematic diagram of the three-dimensional structure of a linear drive mechanism provided in Example 1 of the present invention;

[0021] FIG2 is an exploded perspective view of the linear drive mechanism according to the first embodiment of the present invention;

[0022] FIG3 is a cross-sectional view taken along line AA of FIG1 ;

[0023] FIG4 is a schematic diagram of the three-dimensional structure of a linear drive mechanism provided in Embodiment 2 of the present invention;

[0024] FIG5 is a cross-sectional view taken along line BB in FIG4 .

[0025] Among them, 100, linear drive mechanism; 1, housing; 2, front cover; 3, rear cover; 4, stator; 5, rotor; 51, rotating shaft; 511, shaft stop; 52, permanent magnet; 6, rolling screw; 61, center screw; 611, screw body; 6111, second ball groove; 612, extension part; 62, screw nut; 621, first ball groove; 63, first gear ring; 64, second gear ring; 65, annular screw column; 66, ball; 7, first bearing; 8, second bearing; 9, position sensor; 91, acquisition part; 92, rotating part; 10, base. Modes for Carrying Out the Invention

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1

[0028] As shown in Figures 1 to 3, an embodiment of the present invention provides a linear drive mechanism 100, which includes a housing 1, a front cover 2 and a rear cover 3 respectively fixed to opposite ends of the housing 1, a stator 4 arranged in the housing 1, and a hollow rotor 5 arranged in the stator 4, wherein the stator 4 drives the rotor 5 to rotate; the linear drive mechanism 100 also includes a rolling screw 6 sleeved in the rotor 5, a first bearing 7 sleeved on the rotor 5 and fixed to one end of the rear cover 3, and a second bearing 8 sleeved on the rolling screw 6 and fixed in the housing 1.

[0029] In this embodiment, the front cover 2 and the rear cover 3 are fixed to the housing 1 by welding to improve the stability of the connection.

[0030] Specifically, the rotor 5 includes a hollow rotating shaft 51 disposed in the casing 1 and a plurality of permanent magnets 52 spaced around the rotating shaft 51 and fixed to the outer wall of the rotating shaft 51; the plurality of permanent magnets 52 are spaced apart from the stator 4, and the first bearing 7 and the second bearing 8 are respectively sleeved on the rotating shaft 51.

[0031] In this embodiment, the motor formed by the stator 4 and the rotor 5 has an 8-pole 9-slot structure, a 10-pole 12-slot structure, a 14-pole 12-slot structure, a 14-pole 15-slot structure, a 16-pole 15-slot structure, or a 16-pole 18-slot structure, where "pole" refers to a permanent magnet pole and "slot" refers to a stator slot.

[0032] Specifically, the rolling screw 6 includes a center screw 61 arranged on the inner circumference of the rotor 5 and passing through the front cover 2, and a screw nut 62 sleeved on the center screw 61 and forming a rotational connection with the center screw 61; the screw nut 62 is fixed in the second bearing 8, and the screw nut 62 is formed on the inner circumference of one end of the rotor 5 close to the front cover 2. The rotation of the rotor 5 drives the screw nut 62 to rotate, so that the screw nut 62 rotates to drive the center screw 61 to realize linear telescopic motion.

[0033] In this embodiment, the screw nut 62 is formed on the inner circumference of one end of the rotating shaft 51 close to the front cover 2 , that is, the screw nut 62 and the rotating shaft 51 are an integrally formed structure.

[0034] The inner side of one end of the rotor 5 close to the front cover 2 protrudes and extends along its radial direction to form a protrusion; the screw nut 62 is formed on the inner circumference side of the protrusion close to the central screw 61.

[0035] The rolling screw 6 is a planetary roller screw, and the screw nut 62 is provided with an internal thread structure on the side close to the center screw 61; the center screw 61 includes a screw body 611 arranged on the inner circumference of the rotor 5 and an extension portion 612 formed by extending from one end of the screw body 611 close to the front cover 2, and the outer circumference of the screw body 611 is provided with an external thread structure; the screw nut 62 is engaged with the external thread structure of the screw body 611 through the internal thread structure to achieve a rotational connection.

[0036] The screw nut 62 can be understood as the internal thread structure portion in the rotating shaft 51, or the portion of the rotating shaft 51 having the internal thread structure, or the inner circumferential side portion of the rotating shaft 51 having the internal thread structure.

[0037] The rolling screw 6 also includes a first gear ring 63 and a second gear ring 64, respectively fixed to the ends of the screw nut 62, and a plurality of annular screw posts 65 spaced apart around the central screw 61. Each annular screw post 65 has an external screw thread structure on its outer circumference. The ends of each annular screw post 65 are respectively fixed to the first gear ring 63 and the second gear ring 64, forming a rotational connection. The external screw thread structure of each annular screw post 65 meshes with the external thread structure of the screw body 611, and the external screw thread structure of each annular screw post 65 also meshes with the internal thread structure of the screw nut 62. In other words, the rolling screw 6 in this embodiment is a planetary roller screw.

[0038] The annular screw column 65 is a column with a threaded structure on its outer wall, and its two ends are flat structures for easy installation, but the part in contact with the first gear ring 63 or the second gear ring 64 needs to be provided with a gear structure.

[0039] The first gear ring 63 and the second gear ring 64 are respectively in contact with the two ends of the annular screw column 65 through gear meshing, so that the two ends of the annular screw column 65 are respectively rotatably arranged between the first gear ring 63 and the second gear ring 64.

[0040] The length of the screw body 611 is the same as the length of the rotor 5, which is actually the same as the length of the rotating shaft 51. Of course, according to actual needs, the length of the screw body 611 can also be greater than the length of the rotating shaft 51, or at least enable the internal thread structure to engage with the external thread structure of the annular screw column 65.

[0041] The length of the screw nut 62 is 1 / 8 to 3 / 4 of the length of the rotor 5. This design can greatly shorten the processing length of the thread structure of the screw nut 62, thereby reducing the processing difficulty of the screw nut 62 and ensuring that the screw nut 62 can drive the center screw 61. At the same time, due to the short processing time, the accuracy of the screw nut 62 can be better maintained.

[0042] Specifically, the first bearing 7 and the second bearing 8 are respectively located on opposite sides of the stator 4 and spaced apart from the stator 4 .

[0043] In this embodiment, the outer wall of the rotor 5 protrudes to form a shaft stop 511. The end of the second bearing 8 closest to the front cover 2 abuts the front cover 2, while the end of the second bearing 8 farther from the front cover 2 abuts the shaft stop 511. This arrangement ensures that the second bearing 8 can limit the axial direction of the rotating shaft 51 and the screw nut 62. Accordingly, the first bearing 7 can also be fixed in the same or similar manner.

[0044] The shaft stop 511 is provided on the rotating shaft 51 of the rotor 5 ; the first bearing 7 is a deep groove ball bearing; and the second bearing 8 is a four-point contact bearing or an angular contact bearing.

[0045] Specifically, the linear drive mechanism 100 also includes a position sensor 9; the position sensor 9 includes a collecting portion 91 fixed to the rear cover 3 and a rotating portion 92 fixed to one end of the rotor 5 close to the rear cover 3, and the collecting portion 91 and the rotating portion 92 are opposite and spaced apart.

[0046] In this embodiment, the linear drive mechanism 100 also includes a base 10 that is sleeved and fixed on one end of the rotor 5 close to the rear cover 3 and seals the end of the rotor 5 close to the rear cover 3, and the rotating part 92 is fixed to the base 10; the base 10 abuts against the side of the first bearing 7 close to the rear cover 3.

[0047] The base 10 is sleeved on the rotating shaft 51 of the rotor 5 , and the edges of the joint surfaces of the two are welded to enhance the stability of the connection.

[0048] The position sensor 9 is a Hall position sensor 9, a magnetic coding position sensor 9 or an optical coding position sensor 9. If the Hall position sensor 9 is selected, the Hall position sensor 9 is directly fixed to the base 10.

[0049] When the rotor 5 of the linear drive mechanism 100 of this embodiment rotates, that is, when the screw nut 62 rotates, the screw nut 62 does not move axially; during the rotation process, the rotating shaft 51 will transmit the torque to the center screw 61 through the thread structure and the gear structure, thereby converting it into thrust. Because the screw nut 62 is restricted and cannot move axially, according to the interaction of forces, the center screw 61 will be pushed to move axially.

[0050] The linear drive mechanism 100 of this embodiment forms the screw nut 62 of the rolling screw 6 on the inner peripheral side of the end of the rotor 5 close to the front cover 2. This not only improves the integration of the rolling screw 6 and the rotor 5, thereby reducing the volume space of the linear drive mechanism 100 and meeting the demand for miniaturization, but also improves the bearing capacity of the rolling screw 6. At the same time, since the screw nut 62 is not completely formed along the entire length of the rotor 5, the processing difficulty of the screw nut 62 can also be reduced.

[0051] Example 2

[0052] The difference between the embodiment of the present invention and the first embodiment is that the screw nut 62 in this embodiment is not provided with a threaded structure on the side close to the center screw 61, and the outer peripheral side of the screw body 611 is not provided with a threaded structure; the rolling screw 6 is not provided with a first gear ring 63, a second gear ring 64 and an annular screw column 65, that is, this embodiment does not realize the rotational connection between the screw nut 62 and the center screw 61 by means of a threaded structure connection.

[0053] Specifically, in the embodiment of the present invention, in combination with Figures 4 and 5, the rolling screw 6 is a ball screw, and a plurality of first ball grooves 621 in the form of a thread are provided at intervals on one side of the screw nut 62 close to the center screw 61; the center screw 61 includes a screw body 611 provided on the rotor 5 and an extension portion 612 formed by extending from one end of the screw body 611 close to the front cover 2, and a plurality of second ball grooves 6111 in the form of a thread are provided at intervals on the outer peripheral side of the screw body 611; the rolling screw 6 also includes a plurality of balls 66, each ball 66 is sandwiched between a first ball groove 621 and a second ball groove 6111 so that the screw nut 62 forms a rolling connection with the screw body 611.

[0054] The screw nut 62 can be understood as a structural part of the multiple first ball grooves 621 in the rotating shaft 51, or a part of the rotating shaft 51 having a structure with multiple first ball grooves 621, or an inner circumferential side part of the rotating shaft 51 having a structure with multiple first ball grooves.

[0055] That is, this embodiment uses a ball rolling method to achieve the rotational connection between the screw nut 62 and the center screw 61. This means that the rolling screw 6 of this embodiment is a ball screw. Although the method for achieving the rotational connection between the screw nut 62 and the center screw 61 of this embodiment is different from that of the first embodiment, the technical effects achieved by the linear drive mechanism 100 of this embodiment are the same as those achieved by the linear drive mechanism 100 of the first embodiment, and will not be further described here.

[0056] Whether it is the planetary roller screw used in Example 1 or the ball screw used in this embodiment, they are different from the standard center screw in the related art that rotates to push the screw nut to perform linear motion, because the planetary roller screw in Example 1 and the ball screw in Example 2 both rotate the screw nut 62 to push the center screw 61 to perform linear motion.

[0057] In addition, after the execution drive mechanism of the present invention is applied to the joints of the robot, the robot can also achieve the technical effects achieved by the execution drive mechanism in Example 1 or Example 2.

[0058] The above description is only an embodiment of the present invention. It should be pointed out that those skilled in the art can make improvements without departing from the creative concept of the present invention, but these improvements all fall within the scope of protection of the present invention.

Claims

1. A linear drive mechanism, comprising a housing, a front cover and a rear cover respectively fixed to opposite ends of the housing, a stator disposed within the housing, and a hollow rotor disposed within the stator, the stator driving the rotor to rotate; characterized in that, The linear drive mechanism further includes a rolling screw sleeved inside the rotor, a first bearing sleeved on the rotor and fixed to one end of the rear cover, and a second bearing sleeved on the rolling screw and fixed inside the housing; The rolling screw includes a central screw disposed on the inner peripheral side of the rotor and passing through the center of the front cover, and a screw nut sleeved on the central screw and rotatably connected to the central screw; the screw nut is fixed inside the second bearing, the screw nut is formed on the inner peripheral side of one end of the rotor close to the front cover, and the rotation of the rotor drives the screw nut to rotate, so that the rotation of the screw nut drives the central screw to achieve linear telescopic movement.

2. The linear drive mechanism according to claim 1, wherein The rolling screw is a planetary roller screw, and an internal thread structure is provided on one side of the screw nut close to the central screw; the central screw includes a screw body disposed on the inner peripheral side of the rotor and an extension formed by extending from one end of the screw body close to the front cover, and an external thread structure is provided on the outer peripheral side of the screw body; the screw nut is meshed with the external thread structure of the screw body through the internal thread structure to achieve a rotational connection.

3. The linear drive mechanism according to claim 2, wherein The rolling screw further includes a first gear ring and a second gear ring respectively fixed to both ends of the screw nut, and a plurality of annular screw columns spaced around the central screw. A screw column external thread structure is provided on the outer peripheral side of each annular screw column; both ends of each annular screw column are respectively disposed in the first gear ring and the second gear ring and form a rotational connection. The screw column external thread structure of each annular screw column is respectively meshed with the external thread structure of the screw body, and the screw column external thread structure of each annular screw column is also respectively meshed with the internal thread structure of the screw nut.

4. The linear drive mechanism according to claim 1, characterized in that, The rolling screw is a ball screw, and a plurality of first ball grooves formed by recesses and having a threaded shape are spaced on one side of the screw nut close to the central screw; the central screw includes a screw body disposed on the rotor and an extension formed by extending from one end of the screw body close to the front cover, and a plurality of second ball grooves formed by recesses and having a threaded shape are spaced on the outer peripheral side of the screw body; the rolling screw further includes a plurality of balls, and each ball is clamped between a first ball groove and a second ball groove to enable the screw nut and the screw body to form a rolling connection.

5. The linear drive mechanism according to any one of claims 2 to 4, characterized in that, A convex portion is formed by protruding and extending radially along the inner side of one end of the rotor close to the front cover; the screw nut is inserted and formed on the inner peripheral side of the convex portion close to the central screw.

6. The linear drive mechanism according to claim 1, characterized in that, The first bearing and the second bearing are respectively located on opposite sides of the stator and are spaced from the stator; a shaft stop is formed by protruding on the outer side wall of the rotor, one end of the second bearing close to the front cover abuts against the front cover, and one end of the second bearing away from the front cover abuts against the shaft stop.

7. The linear drive mechanism according to claim 1, characterized in that, The length of the screw nut is 1 / 8 - 3 / 4 of the length of the rotor.

8. The linear drive mechanism according to claim 1, characterized in that, The rotor includes a rotating shaft that is hollow and disposed within the housing, and a plurality of permanent magnets that are spaced around the rotating shaft and fixed to the outer sidewall of the rotating shaft; the plurality of permanent magnets are spaced from the stator, the first bearing and the second bearing are respectively sleeved on the rotating shaft, and the lead screw nut is formed on the inner peripheral side of one end of the rotating shaft close to the front cover.

9. The linear drive mechanism according to claim 1, wherein, The motor formed by the stator and the rotor together is an 8-pole 9-slot structure, or a 10-pole 12-slot structure, or a 14-pole 12-slot structure, or a 14-pole 15-slot structure, or a 16-pole 15-slot structure, or a 16-pole 18-slot structure.

10. The linear drive mechanism according to claim 1, characterized in that, The linear drive mechanism further includes a position sensor; the position sensor includes a collecting portion fixed to the rear cover and a rotating portion fixed to one end of the rotor close to the rear cover, and the collecting portion and the rotating portion are opposite and spaced apart.

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