A micro-lead differential planetary roller screw and electric cylinder

Abstract

This application provides a micro-lead differential planetary roller screw and an electric cylinder. By employing a design in which the portion of the screw that meshes with the first roller thread area has the same pitch, the same helix angle, and opposite helix direction as the first roller thread area, or by employing a design in which the portion of the outer sleeve that meshes with the second roller thread area has the same pitch, the same helix angle, and opposite helix direction as the second roller thread area, a constant output lead that is much smaller than the screw thread lead is achieved. This expands the application range of the micro-lead differential planetary roller screw to the micro-lead field.

Description

Technical Field

[0001] This application relates to the field of mechanical technology, and more specifically, to a micro-lead differential planetary roller screw and electric cylinder. Background Technology

[0002] Differential planetary roller screws use rollers and nuts with a helix angle of 0 and a ring tooth structure. This structure produces a differential effect, which reduces the lead of the assembly. However, the differential effect is limited and can only reduce the lead to the millimeter level, but cannot reduce the lead to within one hundred micrometers. Summary of the Invention

[0003] To address the aforementioned issues, the purpose of this application is to provide a micro-lead differential planetary roller screw and electric cylinder.

[0004] In a first aspect, embodiments of this application provide a micro-lead differential planetary roller screw, comprising: a housing and a screw, a first roller, a first nut, a first bearing, an end cap, a first cage, a second cage, and a first coupling structure disposed within the housing;

[0005] The first nut is sleeved on the screw, the outer shell is sleeved on the first nut, the end caps are respectively fixed at both ends of the outer shell, the first bearing is disposed between the end caps and the first nut, and the two ends of the first nut are respectively connected to the end face of the end cap facing the first nut through the first bearing;

[0006] The first retainer and the second retainer are respectively fitted onto both sides of the screw;

[0007] The first retainer is rotatably connected to an end cap located at one end of the housing; the second retainer is rotatably connected to an end cap located on the other side of the housing;

[0008] The two ends of the first roller are rotatably connected to the first cage and the second cage, respectively;

[0009] The first roller is arranged radially between the screw and the first nut;

[0010] The first roller includes a first roller thread region and a first roller ring tooth region. The first roller thread region meshes with a portion of the screw, and the first roller ring tooth region contacts a portion of the first nut. The portion of the screw that meshes with the first roller thread region has the same pitch, the same helix angle, and opposite helix direction to the first roller thread region. The portion of the first nut that contacts the first roller ring tooth region and the first roller ring tooth region both have annular groove structures.

[0011] The first coupling structure is fixedly connected to the outer shell and the first roller, and rotatably connected to the first cage;

[0012] After the second cage rotates, it drives the first roller to revolve around the screw. Since a part of the screw meshes with the threaded area of ​​the first roller, the first roller will also rotate, thereby expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field.

[0013] Secondly, this application also provides a micro-lead differential planetary roller screw, including: a guide rod, a second roller, a second nut, a planetary cage, a second bearing, a second coupling structure, and an outer sleeve;

[0014] The second nut is sleeved on the optical rod, the planetary cage is sleeved on both sides of the second nut and the second nut is located inside the planetary cage, the planetary cage is rotatably connected to the optical rod, the second nut is rotatably connected to the optical rod through a second bearing, and the outer sleeve is sleeved on the planetary cage;

[0015] The two ends of the second roller are rotatably connected to the two ends of the planetary cage, respectively;

[0016] The second roller is arranged radially between the outer sleeve and the second nut along the second nut;

[0017] The second roller includes a second roller thread region and a second roller ring tooth region. The second roller thread region engages with a portion of the outer sleeve, and the second roller ring tooth region contacts a portion of the second nut. The portion of the outer sleeve that engages with the second roller thread region has the same pitch, the same helix angle, and opposite helix direction to the second roller thread region. The portion of the second nut that contacts the second roller ring tooth region and the second roller ring tooth region both have annular groove structures.

[0018] The second coupling structure is fixedly connected to the optical rod and the second roller respectively, and rotatably connected to the planetary cage;

[0019] After the cage rotates, it drives the second roller to revolve around the second nut. Since the threaded area of ​​the second roller meshes with a part of the outer sleeve, the second roller will also rotate, thereby expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field.

[0020] Thirdly, embodiments of this application also provide a micro-lead electric cylinder, including: the micro-lead differential planetary roller screw described in the first aspect or the second aspect above.

[0021] In the embodiments of this application, the solutions provided by the first aspect and the third aspect including the first aspect, in the micro-lead differential planetary roller screw, the two ends of the first roller are rotatably connected to the first cage and the second cage, respectively. The first roller is arranged radially between the screw and the first nut. The threaded area of ​​the first roller meshes with a portion of the screw. The portion of the screw that meshes with the threaded area of ​​the first roller has the same pitch, the same helix angle, and opposite helix direction as the threaded area of ​​the first roller. Compared with the related art, which uses rollers and nuts with a helix angle of 0 and a ring tooth structure in differential planetary roller screws, this method, by using a portion of the screw that meshes with the threaded area of ​​the first roller with the same pitch, the same helix angle, and opposite helix direction, provides a more efficient solution. The design achieves a constant output lead much smaller than the screw thread lead, expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field. Furthermore, the first coupling structure between the first roller and the screw ensures structural coupling between them, preventing slippage during rotation. This coupling structure keeps the axes of the first roller and screw parallel, preventing tilting and ensuring constant ratios of the first roller's rotational speed to its revolution speed, and the first roller's revolution speed to the first nut's rotational speed. This improves the roller screw's service life and maximum allowable rotational speed, while also reducing noise during operation. The output lead is unaffected by nut load, screw speed, or preload.

[0022] In the embodiments of this application, the solutions provided by the second aspect and the third aspect including the second aspect described above, in the micro-lead differential planetary roller screw, the two ends of the second roller are rotatably connected to the two ends of the planetary cage, respectively. The second roller is arranged radially between the outer sleeve and the second nut. The second roller includes a second roller threaded area, which meshes with a portion of the outer sleeve. The portion of the outer sleeve that meshes with the second roller threaded area has the same pitch and helix angle as the second roller threaded area, but the helix direction is opposite. Compared with the related art, which uses rollers and nuts with a helix angle of 0 and a ring tooth structure in differential planetary roller screws, this method, by using a portion of the outer sleeve that meshes with the second roller threaded area with the same pitch and helix angle, provides a more efficient and efficient solution. The design of equal angles and opposite helix directions achieves a constant output lead much smaller than the screw thread lead, expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field. Furthermore, the second coupling structure between the second roller and the outer sleeve ensures structural coupling between the second roller and the second nut, preventing slippage during rotation. This second coupling structure keeps the axes of the second roller and the outer sleeve parallel, preventing tilting of the second roller. This ensures that the ratio of the second roller's rotational speed to its revolution speed, and the ratio of the second roller's revolution speed to the second nut's rotational speed, are constant, thereby improving the service life and maximum allowable rotational speed of the roller screw. It also reduces noise generated during operation, and the output lead is unaffected by nut load, screw speed, and preload.

[0023] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A cross-sectional view of a micro-lead differential planetary screw provided in Embodiment 1 of this application is shown;

[0026] Figure 2 A left view of the micro-lead differential planetary screw provided in an embodiment of this application is shown;

[0027] Figure 3The embodiments provided in this application are shown. Figure 1 A magnified view of a portion of point A;

[0028] Figure 4 A three-dimensional structural schematic diagram of the first retainer provided in an embodiment of this application is shown;

[0029] Figure 5 A three-dimensional structural schematic diagram of the second retainer provided in an embodiment of this application is shown;

[0030] Figure 6 This illustration shows a structural schematic diagram of a micro-lead electric cylinder provided in an embodiment of this application;

[0031] Figure 7 A cross-sectional view of another microlead differential planetary roller screw provided in an embodiment of this application is shown;

[0032] Figure 8 A schematic diagram of another micro-lead electric cylinder provided in an embodiment of this application is shown. Detailed Implementation

[0033] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0035] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0036] Differential planetary roller screws use rollers and nuts with a helix angle of 0 and a ring tooth structure. This structure produces a differential effect, which reduces the lead of the assembly. However, the differential effect is limited and can only reduce the lead to the millimeter level, but cannot reduce the lead to within one hundred micrometers.

[0037] Based on this, the following embodiments of this application propose a micro-lead differential planetary roller screw and an electric cylinder. Due to the design that the portion of the screw meshing with the threaded area of ​​the first roller has the same pitch, the same helix angle, and opposite helix direction as the threaded area of ​​the first roller, or the design that the portion of the outer sleeve meshing with the threaded area of ​​the second roller has the same pitch, the same helix angle, and opposite helix direction, a constant output lead much smaller than the screw thread lead is achieved functionally. This expands the application range of the micro-lead differential planetary roller screw to the micro-lead field. Furthermore, the first roller and the screw have a first coupling structure, structurally coupling the first roller and the first nut. No slippage occurs between the first roller and the screw during rotation, ensuring that the ratio of the first roller's rotational speed to its revolution speed, and the ratio of the first roller's revolution speed to the first nut's rotational speed are constant values. This improves the service life and maximum allowable rotational speed of the roller screw.

[0038] In the following embodiments, the term "microlead" refers to a lead of approximately tens to hundreds of micrometers.

[0039] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0040] Example 1

[0041] See Figure 1 The cross-sectional view of the micro-lead differential planetary screw shown is shown below. Figure 2 The left view of the microlead differential planetary screw shown, see also Figure 3 shown Figure 1 A magnified view of the area at point A (see attached diagram). Figure 4 A three-dimensional structural schematic diagram of the first cage is shown below. (See also...) Figure 5 The schematic diagram of the three-dimensional structure of the second cage shown in this embodiment proposes a micro-lead differential planetary roller screw, including: a housing 4 and a screw 1, a first roller 2, a first nut 3, a first bearing 6, an end cap 5, a first cage 7, a second cage 8 and a first coupling structure 9 disposed in the housing 4.

[0042] The end cap 5 is annular. The outer diameter of the first nut 3 is smaller than the inner diameter of the outer shell 4.

[0043] The first nut 3 is sleeved on the screw 1, the outer shell 4 is sleeved on the first nut 3, the end caps 5 are respectively fixed at both ends of the outer shell 4, the first bearing 6 is disposed between the end caps 5 and the first nut 3, and the two ends of the first nut 3 are respectively connected to the end face of the end cap 5 facing the first nut 3 through the first bearing 6.

[0044] The aforementioned screw 1 and the aforementioned housing 4 are also respectively connected to the outside. Specifically, the aforementioned screw 1 is connected to the driven object; the aforementioned housing 4 is fixedly connected to an external structure that serves to fix the micro-lead differential planetary screw.

[0045] Specifically, there are two first bearings 6, both of which are bearings capable of withstanding unidirectional axial loads, or at least one of the first bearings 6 is a four-point contact ball bearing capable of withstanding bidirectional axial loads.

[0046] The bearing capable of withstanding unidirectional axial loads may be, but is not limited to, angular contact bearings, thrust ball bearings, and cylindrical roller bearings.

[0047] The first retainer 7 and the second retainer 8 are respectively fitted on both sides of the screw 1; the first retainer 7 is rotatably connected to the end cap 5 located at one end of the outer casing 4; the second retainer 8 is rotatably connected to the end cap 5 located on the other side of the outer casing 4.

[0048] Specifically, the first retainer 7 has a through hole 701 in the middle and the second retainer 8 has a through hole 801 in the middle; the first retainer 7 is sleeved on the screw 1 through the through hole 701 and the second retainer 8 is sleeved on the screw 1 through the through hole 801.

[0049] In one embodiment, the axes of the screw 1, the first nut 3, and the outer casing 4 coincide.

[0050] The two ends of the first roller 2 are rotatably connected to the first cage 7 and the second cage 8, respectively. The first roller 2 is arranged radially between the screw 1 and the first nut 3. The first roller 2 includes a first roller thread area 201 and a first roller ring tooth area 202. The first roller thread area 201 engages with a portion of the screw 1, and the first roller ring tooth area 202 contacts a portion of the first nut 3. The portion of the screw 1 that engages with the first roller thread area 201 has the same pitch, the same helix angle, and opposite helix direction as the first roller thread area 201. The portion of the first nut 3 that contacts the first roller ring tooth area 202 and the first roller ring tooth area 202 both have annular groove structures. There are multiple first rollers 2.

[0051] The first coupling structure 9 is fixedly connected to the outer shell 4 and the first roller 2, respectively, and is rotatably connected to the first retainer 7.

[0052] After the second cage 8 rotates, it drives the first roller 2 to revolve around the screw 1. Since a part of the screw 1 meshes with the threaded area 201 of the first roller, the first roller 2 will also rotate, thereby expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field.

[0053] The first retainer 7 and the second retainer 8 are respectively mounted on the inner annular sidewall of the end cover 5 via bearings.

[0054] Specifically, the first roller thread area 201 is located in the middle of the first roller 2, and the first roller ring tooth area 202 is located on both sides of the first roller 2; wherein, the outer diameter of the first roller thread area 201 is larger than the outer diameter of the first roller ring tooth area 202; the outer side wall of the screw 1 is provided with a screw thread area 101 that meshes with the first roller thread area; both ends of the inner side wall of the first nut 3 are provided with nut ring tooth areas 301 that contact the first roller ring tooth area 202, and between the nut ring tooth areas 301 at both ends of the first nut 3, the inner side wall of the first nut 3 is also provided with a first ring wall area 302 that is opposite to the first roller thread area 201; wherein, the first roller thread area 201 does not contact the first ring wall area 302, and the first roller ring tooth area 202 does not contact the screw thread area 101.

[0055] Among them, the screw thread area 101 is the part of the screw 1 that meshes with the first roller thread area 201.

[0056] The nut ring tooth region 301 is the portion of the first nut 3 that contacts the first roller ring tooth region 202.

[0057] Specifically, the first retainer 7 is a stepped shaft, the small diameter end of the first retainer 7 is rotatably connected to the end cover 5, and the large diameter end of the first retainer 7 extends to the outside of the end cover 5; a first mounting post 703 is provided on the side of the large diameter end of the first retainer 7 away from the end cover 5.

[0058] The structure of the second cage 8 is similar to that of the first cage 7, and will not be described in detail here.

[0059] The first retainer 703 is provided with a first retainer mounting hole 702 at one end rotatably connected to the first roller 2, and the second retainer 8 is provided with a second retainer mounting hole 802 at one end rotatably connected to the first roller 2; the two ends of the first roller 2 are rotatably connected to the first retainer mounting hole 702 and the second retainer mounting hole 802 respectively by bearings.

[0060] Here, the number of first mounting posts 703 is the same as the number of first retainer mounting holes 702 and their positions correspond.

[0061] The first retainer 7 and the second retainer 8 are rotatably mounted on the inner wall of the end cover 5 via the first bearing (not shown in the figure), and the two ends of the first roller 2 are rotatably mounted in the first retainer mounting hole 702 and the second retainer mounting hole 802 via the first bearing (not shown in the figure).

[0062] In one embodiment, the first retainer mounting hole 702 and the second retainer mounting hole 802 are respectively symmetrically arranged about the axis of the first retainer 7 and the second retainer 8.

[0063] The end of the first roller 2 located in the first retainer mounting hole 702 extends outward to form a first extension.

[0064] like Figure 2 As shown, in one embodiment, the first coupling structure 9 includes: an internal gear ring 901, a first gear 902, and a second gear 903.

[0065] The aforementioned internal gear ring 901 is fixedly connected to the inner wall of the aforementioned outer casing 4; the aforementioned second gear 903 is rotatably connected to the aforementioned first mounting post 703; the aforementioned first gear 902 is fixedly connected to the aforementioned first extension formed at the end of the aforementioned first roller 2; the aforementioned first gear 902 meshes with the corresponding second gear 903, and the aforementioned second gear 903 also meshes with the aforementioned internal gear ring 901. The second gear 903 mainly serves to change the transmission direction, making it possible for the first coupling structure to rotate, thereby ensuring that the ratio of the roller's rotational speed to its revolution speed, and the ratio of the roller's revolution speed to the nut's rotational speed are all constant values.

[0066] In one embodiment, the second gear 903 may be a single-stage gear or a multi-stage gear.

[0067] When the second gear 903 is a single-stage gear, the structure of the first coupling structure 9 is as described above.

[0068] Optionally, when the second gear 903 is a multi-stage gear, the first coupling structure 9 may further include: an internal gear ring 901, a first gear 902, and a multi-stage gear; the internal gear ring 901 is fixedly connected to the inner wall of the outer casing 4; the multi-stage gear is rotatably connected to the first mounting post 703; the first gear 902 is fixedly connected to the first extension formed at the end of the first roller 2; the first gear 902 meshes with the last stage gear in the corresponding multi-stage gear 903, and the first stage gear in the multi-stage gear meshes with the internal gear ring 901. The second gear 903, which uses a multi-stage gear, mainly serves to change the transmission direction, making the rotation of the first coupling structure possible, so that the ratio of the roller's rotational speed to its revolution speed, and the ratio of the roller's revolution speed to the nut's rotational speed are all constant values.

[0069] See Figure 6 The diagram shows a micro-lead electric cylinder. This embodiment proposes a micro-lead electric cylinder, including the aforementioned micro-lead differential planetary roller screw, connecting shaft 10, and actuator 11. The other end of the second cage 8 of the micro-lead differential planetary roller screw extends out of the end cap 5. The connecting shaft 10 is a barrel with one end sealed and the other end open. The open end of the connecting shaft 10 is fixedly connected to the extended end of the second cage 8. The output shaft of the actuator 11 is fixedly connected to the sealed end of the connecting shaft 10.

[0070] Specifically, a first threaded hole 803 is provided on the extended end sidewall of the second retainer 8, and a second threaded hole 1001 is provided on the open end sidewall of the connecting shaft 10. The first threaded hole 803 and the second threaded hole 1001 are connected by a bolt 12.

[0071] In one implementation, actuator 11 may be, but is not limited to, a brushed motor and a brushless motor.

[0072] During operation: the screw 1 and the housing 4 are fixedly connected to the outside. The actuator 11 drives the second cage 8 to rotate. Under the action of the second cage 8, the first roller 2 will revolve around the screw 1. Since the screw thread area 101 of the screw 1 meshes with the first roller thread area 201, the first roller 2 will also rotate, thus expanding the application range to the field of micro-lead.

[0073] During the rotation of the first roller 2, the first gear 902, which is fixedly connected to the first roller 2, will rotate, thereby driving the multi-stage gear 903 meshing with the first gear 902 to rotate. The multi-stage gear 903 will rotate around the internal gear ring 901, thereby maintaining the positional relationship between the first roller 2 and the outer shell 4 and preventing the first roller 2 from tilting due to slippage. Since the screw 1 and the outer shell 4 are fixedly connected to the outside respectively, the first roller 2 and the outer shell 4 do not slip, thus achieving the goal of preventing slippage between the first roller 2 and the screw 1.

[0074] The micro-lead differential planetary roller screw and micro-lead electric cylinder proposed in this embodiment have the following characteristics:

[0075] In the micro-lead differential planetary roller screw and electric cylinder, when the screw is subjected to axial load during operation, the load is transmitted from the screw to the first roller, then from the first roller to the first nut, then from the first nut to the first bearing, and finally from the first bearing to the housing. This structural feature not only improves the axial load capacity of the system, but also allows the first nut to rotate freely around the first bearing during system operation. The rotation of the first bearing disperses the frictional force generated at the meshing point of the first roller and the first nut along the circumferential direction, further reducing frictional force, improving the transmission efficiency of the system, reducing the noise generated during the operation of the first roller and the screw, and simultaneously improving the service life and maximum permissible rotational speed of the electric cylinder.

[0076] In summary, this embodiment proposes a micro-lead differential planetary roller screw and a micro-lead electric cylinder. In the micro-lead differential planetary roller screw, the two ends of the first roller are rotatably connected to the first cage and the second cage, respectively. The first roller is arranged radially between the screw and the first nut. The threaded area of ​​the first roller meshes with a portion of the screw. The portion of the screw that meshes with the threaded area of ​​the first roller has the same pitch, the same helix angle, and opposite helix direction as the threaded area of ​​the first roller. Compared with the related technology that uses rollers and nuts with a helix angle of 0 and a ring tooth structure in differential planetary roller screws, this embodiment achieves a significant improvement by using a portion of the screw that meshes with the threaded area of ​​the first roller with the same pitch, the same helix angle, and opposite helix direction. The design achieves a constant output lead much smaller than the screw thread lead, expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field. Furthermore, the first coupling structure between the first roller and the screw ensures structural coupling between them, preventing slippage during rotation. This coupling structure keeps the axes of the first roller and screw parallel, preventing tilting and ensuring constant ratios of the first roller's rotational speed to its revolution speed, and the first roller's revolution speed to the first nut's rotational speed. This improves the roller screw's service life and maximum allowable rotational speed, while also reducing noise during operation. The output lead is unaffected by nut load, screw speed, or preload.

[0077] Example 2

[0078] See Figure 7The cross-sectional view shown is of another type of micro-lead differential planetary roller screw. This embodiment proposes a micro-lead differential planetary roller screw, including: a guide rod a, a second roller b, a second nut c, a planetary cage d, a second bearing e, a second coupling structure f, and an outer sleeve g.

[0079] The second nut c is sleeved on the polished rod a, the planetary cage d is sleeved on both sides of the second nut c and the second nut c is located inside the planetary cage d, the planetary cage d is rotatably connected to the polished rod a, the second nut c is rotatably connected to the polished rod a through the second bearing e, and the outer sleeve g is sleeved on the planetary cage d.

[0080] Among them, the axes of the smooth rod a, the second nut c, and the outer sleeve g coincide.

[0081] The two ends of the second roller b are rotatably connected to the two ends of the planetary cage d, respectively; the second roller b is arranged radially between the outer sleeve g and the second nut c along the second nut c. There are multiple second rollers b.

[0082] The aforementioned second roller b includes: a second roller threaded area b01 and a second roller ring tooth area b02. The second roller threaded area b01 engages with a portion of the outer sleeve g, and the second roller ring tooth area b02 contacts a portion of the second nut c. The portion of the outer sleeve g that engages with the second roller threaded area b01 has the same pitch and helix angle as the second roller threaded area b01, but the helix direction is opposite. The portion of the second nut b that contacts the second roller ring tooth area b02 and the second roller ring tooth area b02 both have annular groove structures.

[0083] The aforementioned second coupling structure f is fixedly connected to the aforementioned optical rod a and the aforementioned second roller b, and is rotatably connected to the aforementioned planetary cage d.

[0084] After the cage d rotates, it drives the second roller b to revolve around the second nut c. Since the threaded area b01 of the second roller meshes with a part of the outer sleeve g, the second roller b will also rotate, thereby expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field.

[0085] The micro-lead differential planetary roller screw proposed in this embodiment further includes: a spline shaft g02; a spline hole a01 is provided in the above-mentioned guide rod a, the spline hole a01 is coaxial with the above-mentioned guide rod a, the spline shaft g02 is inserted into the above-mentioned spline hole a01, the spline shaft g02 can move in the above-mentioned spline hole a01, and restrict the above-mentioned guide rod a from rotating around the axis of the above-mentioned guide rod itself.

[0086] The micro-lead differential planetary roller screw proposed in this embodiment also includes: a linear sensor i; and a mounting hole g021 is provided in the spline shaft g02, the mounting hole g021 being coaxial with the spline shaft g02.

[0087] The aforementioned linear sensor i includes: a grating ruler i01, a reading head i02, and a mounting plate i03; the grating ruler i01 is disposed within the mounting hole g021, the mounting plate i03 is located within the spline hole a01 and one end is fixed to the optical rod a, and the reading head i02 is mounted on the mounting plate i03. The reading head i02 can acquire data on the position change on the grating ruler i01 and is electrically connected to a data processing device.

[0088] In one implementation, the optical grating ruler i01 can be replaced by a magnetic grating ruler.

[0089] The micro-lead differential planetary roller screw proposed in this embodiment has a second roller thread region b01 located in the middle of the second roller b, and a second roller ring tooth region b02 located on both sides of the second roller b; wherein the outer diameter of the second roller thread region b01 is larger than the outer diameter of the second roller ring tooth region b02.

[0090] The inner wall of the outer sleeve g is provided with an outer sleeve thread area g01 that meshes with the second roller thread area b01; the outer walls of the second nut c are provided with second nut ring tooth areas b02 at both ends that contact the second roller ring tooth area b02; between the second nut ring tooth areas b02 at both ends of the second nut c, the outer wall of the second nut c is also provided with a second annular wall area c02 that is opposite to the second roller thread area b01; wherein the second roller thread area b01 does not contact the second annular wall area c02, and the second roller ring tooth area b02 does not contact the outer sleeve thread area g01.

[0091] The planetary cage d and the second roller b are rotatably connected at both ends and are provided with mounting holes. The two ends of the second roller are rotatably connected to the mounting holes located at both ends of the planetary cage via bearings.

[0092] A second mounting post d01 is provided on one end of the planetary cage d away from the second nut b; the end of the second roller b located on one end of the planetary cage d away from the second nut c extends outward to form a second extension.

[0093] The aforementioned second coupling structure f includes: a third gear f01, a fourth gear f02, and a fifth gear f03; the third gear f01 is fixedly connected to the outer wall of the aforementioned guide rod a; the fourth gear f02 is rotatably connected to the aforementioned second mounting post d01; the fifth gear f03 is fixedly connected to the aforementioned second extension at the end of the aforementioned second roller b; the fourth gear f02 meshes with the corresponding fifth gear f03 and also meshes with the aforementioned third gear f01. The fourth gear f02 mainly serves to change the transmission direction, making the rotation of the second coupling structure f possible, thereby ensuring that the ratio of the rotational speed to the revolution speed of the second roller b, and the ratio of the revolution speed of the second roller b to the rotational speed of the second nut c, are both constant values.

[0094] Optionally, a bearing spacer ring j is provided between the smooth rod a and the second nut c. The two ends of the bearing spacer ring j abut against the second bearing e respectively. The bearing spacer ring j facilitates the transfer of load and makes the structure more stable.

[0095] See Figure 8 The schematic diagram of another type of electric cylinder with a small lead is shown. This embodiment also proposes an electric cylinder with a small lead, including: the above-mentioned small lead differential planetary roller screw, coupling h and actuator 11. The actuator 11 is fixedly connected to the planetary cage d through the coupling h, and the inner diameter of the outer sleeve g is larger than the outer diameter of the actuator 11.

[0096] The outer sleeve g and the actuator 11 are respectively fixedly connected to the outside; the outer sleeve g is connected to the driven object; the actuator 11 is fixedly connected to the external structure that serves to fix the small lead differential planetary screw.

[0097] During operation: the outer sleeve g and the actuator 11 are respectively fixedly connected to the outside. The actuator 11 drives the planetary cage d to rotate. Under the action of the planetary cage d, the second roller b will revolve around the second nut c. The threaded area b01 of the second roller meshes with the threaded area g01 of the outer sleeve g, so the second roller b will also rotate, thereby expanding the application range to the field of micro-lead.

[0098] During the rotation of the second roller b, the fifth gear f03, which is fixedly connected to it, will rotate, thereby driving the fourth gear f02, which meshes with the fifth gear f03, to rotate. The fourth gear f02 will rotate around the third gear f01, thus maintaining the positional relationship between the second roller b and the guide rod a. This prevents the second roller b from tilting due to slippage. Since there is no rotation between the guide rod a and the outer sleeve g, no slippage occurs between the second roller b and the guide rod a, thus achieving the goal of preventing slippage between the second roller b and the outer sleeve g.

[0099] The micro-lead differential planetary roller screw and electric cylinder proposed in this embodiment have the following characteristics:

[0100] 1. In the micro-lead differential planetary roller screw and electric cylinder, when the outer sleeve is subjected to axial load during operation, the load is transferred from the outer sleeve to the second roller, then from the second roller to the second nut, then from the second nut to the second bearing, and finally from the second bearing to the guide rod. This structural feature not only improves the axial load capacity of the system, but also allows the second nut to rotate freely around the second bearing during system operation. The rotation of the second bearing disperses the frictional force generated at the meshing point of the second roller and the second nut along the circumferential direction, further reducing frictional force, improving the transmission efficiency of the system, reducing the noise generated during the operation of the second roller and the outer sleeve, and simultaneously improving the service life and maximum permissible rotational speed of the electric cylinder.

[0101] 2. The micro-lead differential planetary roller screw and electric cylinder, through the setting of linear sensors, can achieve precise and effective positioning of the electric cylinder. The data processing equipment can determine the position status of the outer sleeve based on the position information measured by the linear sensors, ensuring the stability and reliability of the electric cylinder's working state. It has a compact structure, is easy to install and use, has a high degree of automation, and is safe and reliable. Compared with related technologies, this detection method has no angular hysteresis, effectively reducing the deviation between the determined position of the outer sleeve and the actual position of the outer sleeve, thereby improving control accuracy.

[0102] In summary, this embodiment proposes a micro-lead differential planetary roller screw and a micro-lead electric cylinder. In the micro-lead differential planetary roller screw, the two ends of the second roller are rotatably connected to the two ends of the planetary cage, respectively. The second roller is arranged radially between the outer sleeve and the second nut. The second roller includes a second roller threaded area, which meshes with a portion of the outer sleeve. The portion of the outer sleeve that meshes with the second roller threaded area has the same pitch and helix angle as the second roller threaded area, but the helix direction is opposite. Compared with the related technology that uses rollers and nuts with a helix angle of 0 and a ring tooth structure in differential planetary roller screws, this embodiment achieves a significant improvement by using a portion of the outer sleeve that meshes with the second roller threaded area with the same pitch and helix angle. The design of equal angles and opposite helix directions achieves a constant output lead much smaller than the screw thread lead, expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field. Furthermore, the second coupling structure between the second roller and the outer sleeve ensures structural coupling between the second roller and the second nut, preventing slippage during rotation. This second coupling structure keeps the axes of the second roller and the outer sleeve parallel, preventing tilting of the second roller. This ensures that the ratio of the second roller's rotational speed to its revolution speed, and the ratio of the second roller's revolution speed to the second nut's rotational speed, are constant, thereby improving the service life and maximum allowable rotational speed of the roller screw. It also reduces noise generated during operation, and the output lead is unaffected by nut load, screw speed, and preload.

[0103] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A micro-lead differential planetary roller screw, characterized in that, include: The housing and the screw, first roller, first nut, first bearing, end cap, first cage, second cage and first coupling structure disposed within the housing; The first nut is sleeved on the screw, the outer shell is sleeved on the first nut, the end caps are respectively fixed at both ends of the outer shell, the first bearing is disposed between the end caps and the first nut, and the two ends of the first nut are respectively connected to the end face of the end cap facing the first nut through the first bearing; The first retainer and the second retainer are respectively fitted onto both sides of the screw; The first retainer is rotatably connected to an end cap located at one end of the housing; the second retainer is rotatably connected to an end cap located on the other side of the housing; The two ends of the first roller are rotatably connected to the first cage and the second cage, respectively; The first roller is arranged radially between the screw and the first nut; The first roller includes a first roller thread region and a first roller ring tooth region. The first roller thread region meshes with a portion of the screw, and the first roller ring tooth region contacts a portion of the first nut. The portion of the screw that meshes with the first roller thread region has the same pitch, the same helix angle, and opposite helix direction to the first roller thread region. The portion of the first nut that contacts the first roller ring tooth region and the first roller ring tooth region both have annular groove structures. The first coupling structure is fixedly connected to the outer shell and the first roller, and rotatably connected to the first cage; After the second cage rotates, it drives the first roller to revolve around the screw. Since a part of the screw meshes with the threaded area of ​​the first roller, the first roller will also rotate, thereby expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field.

2. The micro-lead differential planetary roller screw according to claim 1, characterized in that, The first roller thread area is located in the middle of the first roller, and the first roller ring tooth area is located on both sides of the first roller; wherein, the outer diameter of the first roller thread area is larger than the outer diameter of the first roller ring tooth area. The outer wall of the screw is provided with a screw thread area that meshes with the first roller thread area; the inner wall of the first nut is provided with nut ring tooth areas at both ends that contact the first roller ring tooth area, and between the nut ring tooth areas at both ends of the first nut, the inner wall of the first nut is also provided with a first ring wall area that is opposite to the first roller thread area; wherein, the first roller thread area does not contact the first ring wall area, and the first roller ring tooth area does not contact the screw thread area.

3. The micro-lead differential planetary roller screw according to claim 1, characterized in that, The first retainer is a stepped shaft, the small-diameter end of the first retainer is rotatably connected to the end cap, and the large-diameter end of the first retainer extends to the outside of the end cap; A first mounting post is provided on the side of the large-diameter end of the first retainer away from the end cap; The first retainer has a first retainer mounting hole at one end rotatably connected to the first roller, and the second retainer has a second retainer mounting hole at one end rotatably connected to the first roller; the two ends of the first roller are rotatably connected to the first retainer mounting hole and the second retainer mounting hole respectively via bearings. The end of the first roller located in the first cage mounting hole extends outward to form a first extension.

4. The micro-lead differential planetary roller screw according to claim 3, characterized in that, The first coupling structure includes: an internal gear ring, a first gear, and a second gear; The internal gear ring is fixedly connected to the inner wall of the outer shell; The second gear is rotatably connected to the first mounting post, the first gear is fixedly connected to the first extension formed at the end of the first roller, the first gear meshes with the corresponding second gear, and the second gear also meshes with the internal gear ring.

5. A micro-lead differential planetary roller screw, characterized in that, include: The polished rod, the second roller, the second nut, the planetary cage, the second bearing, the second coupling structure, and the outer sleeve; The second nut is sleeved on the optical rod, the planetary cage is sleeved on both sides of the second nut and the second nut is located inside the planetary cage, the planetary cage is rotatably connected to the optical rod, the second nut is rotatably connected to the optical rod through a second bearing, and the outer sleeve is sleeved on the planetary cage; The two ends of the second roller are rotatably connected to the two ends of the planetary cage, respectively; The second roller is arranged radially between the outer sleeve and the second nut along the second nut; The second roller includes a second roller thread region and a second roller ring tooth region. The second roller thread region engages with a portion of the outer sleeve, and the second roller ring tooth region contacts a portion of the second nut. The portion of the outer sleeve that engages with the second roller thread region has the same pitch, the same helix angle, and opposite helix direction to the second roller thread region. The portion of the second nut that contacts the second roller ring tooth region and the second roller ring tooth region both have annular groove structures. The second coupling structure is fixedly connected to the optical rod and the second roller, respectively, and rotatably connected to the planetary cage; After the cage rotates, it drives the second roller to revolve around the second nut. Since the threaded area of ​​the second roller meshes with a part of the outer sleeve, the second roller will also rotate, thereby expanding the application range of the micro-lead differential planetary roller screw to the micro-lead field.

6. The micro-lead differential planetary roller screw according to claim 5, characterized in that, Also includes: Spline shaft; A spline hole is provided inside the optical rod. The spline hole is coaxial with the optical rod. The spline shaft is inserted into the spline hole and can move within the spline hole, thus restricting the optical rod from rotating around its own axis.

7. The micro-lead differential planetary roller screw according to claim 6, characterized in that, Also includes: Linear sensor; The splined shaft is also provided with a mounting hole, which is coaxial with the splined shaft. The linear sensor includes: a grating ruler, a reading head, and a mounting plate; The grating ruler is disposed in the mounting hole, the mounting plate is located in the spline hole and one end is fixed on the optical rod, and the reading head is mounted on the mounting plate.

8. The micro-lead differential planetary roller screw according to claim 5, characterized in that, The second roller thread area is located in the middle of the second roller, and the second roller ring tooth area is located on both sides of the second roller; wherein, the outer diameter of the second roller thread area is larger than the outer diameter of the second roller ring tooth area; The inner sidewall of the outer sleeve is provided with an outer sleeve thread area that meshes with the second roller thread area; the two ends of the outer sidewall of the second nut are provided with second nut ring tooth areas that contact the second roller ring tooth area, and between the two ends of the second nut ring tooth areas, the outer sidewall of the second nut is also provided with a second ring wall area that is opposite to the second roller thread area; wherein, the second roller thread area does not contact the second ring wall area, and the second roller ring tooth area does not contact the outer sleeve thread area.

9. The micro-lead differential planetary roller screw according to claim 5, characterized in that, The planetary cage is provided with mounting holes at both ends of the second roller rotatably connected to it, and the two ends of the second roller are rotatably connected to the mounting holes located at both ends of the planetary cage via bearings. A second mounting post is provided on the end of the planetary cage that is away from the second nut; The end of the second roller located in the planetary cage away from the second nut extends outward to form a second extension; The second coupling structure includes: a third gear, a fourth gear, and a fifth gear; The third gear is fixedly connected to the outer wall of the guide rod; the fourth gear is rotatably connected to the second mounting post; the fifth gear is fixedly connected to the second extension at the end of the second roller; the fourth gear meshes with the corresponding fifth gear and also meshes with the third gear.

10. An electric cylinder with a very small lead, characterized in that, include: The micro-lead differential planetary roller screw as described in any one of claims 1-4 or any one of claims 5-9.

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