Micro-lead differential-type planetary roller screw and electric cylinder

Abstract

Provided are a micro-lead differential-type planetary roller screw and an electric cylinder. A part of an area in a screw (1) engaged with a first roller threaded zone (201) has the same pitch, the same spiral lifting angle, and opposite spiral direction as the first roller threaded zone (201); alternatively, a part of an area in an outer sleeve (g) engaged with a second roller thread zone (b01) has the same pitch, the same spiral lifting angle, and opposite spiral direction as the second roller thread zone (b01). Thus, a constant output lead that is much smaller than the screw thread lead is achieved, expanding the application range of micro-lead differential planetary roller screws to the micro-lead field.

Description

A micro lead differential planetary roller screw and electric cylinder TECHNICAL FIELD

[0001] The present application relates to the technical field of machinery, in particular to a micro lead differential planetary roller screw and electric cylinder. BACKGROUND

[0002] The rollers and nuts used in the differential planetary roller screw have a helix angle of 0 and a ring tooth structure. Such a structure produces a differential effect to reduce the lead of the assembly, but the differential effect is limited and can only reduce the lead to the millimeter level, but cannot reduce the lead to within one hundred microns. SUMMARY

[0003] To solve the above problems, the purpose of the embodiments of the present application is to provide a micro lead differential planetary roller screw and electric cylinder.

[0004] In a first aspect, the embodiments of the present 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 cover, a first retainer, a second retainer and a first coupling structure arranged in the housing.

[0005] The first nut is sleeved on the screw, the housing is sleeved on the first nut, the end cover is fixed at both ends of the housing respectively, the first bearing is arranged between the end cover and the first nut, and the two ends of the first nut are connected with the end faces of the end cover facing the first nut through the first bearing.

[0006] The first retainer and the second retainer are sleeved on both sides of the screw respectively.

[0007] The first retainer is rotationally connected with the end cover located at one end of the housing, and the second retainer is rotationally connected with the end cover located at the other side of the housing.

[0008] The two ends of the first roller are rotationally connected with the first retainer and the second retainer respectively.

[0009] The first roller is arranged between the screw and the first nut along the radial direction of the screw.

[0010] The first roller comprises a first roller threaded area and a first roller ring tooth area, the first roller threaded area is engaged with a part of the screw rod, and the first roller ring tooth area is in contact with a part of the first nut; wherein the part of the screw rod engaged with the first roller threaded area has the same pitch, the same helix angle and the opposite helical line direction as the first roller threaded area; the part of the first nut in contact with the first roller ring tooth area is also a ring groove structure;

[0011] The first coupling structure is fixedly connected with the shell and the first roller respectively, and is rotationally connected with the first retainer;

[0012] After the second retainer rotates, the first roller revolves around the screw rod, and since the part of the screw rod is engaged with the first roller threaded area, the first roller also rotates, thereby widening the application range of the micro-lead differential planetary roller screw to the micro-lead field.

[0013] In a second aspect, the embodiments of the present application also provide a micro-lead differential planetary roller screw, comprising a light rod, a second roller, a second nut, a planetary retainer, a second bearing, a second coupling structure and an outer sleeve;

[0014] The second nut is sleeved on the light rod, the planetary retainer is sleeved on both sides of the second nut and located in the planetary retainer, the planetary retainer is rotationally connected with the light rod, the second nut is rotationally connected with the light rod through the second bearing, and the outer sleeve is sleeved on the planetary retainer;

[0015] Both ends of the second roller are rotationally connected with both ends of the planetary retainer respectively;

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

[0017] The second roller comprises a second roller threaded area and a second roller ring tooth area, the second roller threaded area is engaged with a part of the outer sleeve, and the second roller ring tooth area is in contact with a part of the second nut; wherein the part of the outer sleeve engaged with the second roller threaded area has the same pitch, the same helix angle and the opposite helical line direction as the second roller threaded area; the part of the second nut in contact with the second roller ring tooth area is also a ring groove structure;

[0018] The second coupling structure is fixedly connected with the light rod and the second roller respectively, and is rotationally connected with the planetary retainer;

[0019] After the rotation of the retainer, the second roller revolves around the second nut, and since the second roller thread area is engaged with the partial area of the outer sleeve, the second roller also rotates, thereby widening the application range of the micro-lead differential planetary roller screw to the micro-lead field.

[0020] In a third aspect, the embodiments of the present application further provide a micro-lead electric cylinder, comprising the micro-lead differential planetary roller screw according to the first aspect or the second aspect.

[0021] In the first aspect and the third aspect including the first aspect of the embodiments of the present application, in the micro-lead differential planetary roller screw, the two ends of the first roller are respectively rotationally connected with the first retainer and the second retainer, the first roller is arranged between the screw rod and the first nut along the radial direction of the screw rod, the first roller thread area in the first roller is engaged with the partial area of the screw rod, the partial area of the screw rod engaged with the first roller thread area has the same pitch, the same helix angle and the opposite helix direction as the first roller thread area, compared with the way of using the roller and the nut with the helix angle of 0 and the ring tooth structure in the differential planetary roller screw in the related art, since the partial area of the screw rod engaged with the first roller thread area has the same pitch, the same helix angle and the opposite helix direction as the first roller thread area, the constant output lead smaller than the screw rod thread lead is realized in function, so that the application range of the micro-lead differential planetary roller screw is widened to the micro-lead field; moreover, the first coupling structure is arranged between the first roller and the screw rod, so that the first roller and the first nut are coupled in structure, the first coupling structure can keep the axes of the first roller and the screw rod always parallel, the first roller does not tilt, the ratio of the rotation speed to the revolution speed of the first roller and the ratio of the revolution speed of the first roller to the rotation speed of the first nut are constant values, thereby improving the service life and the maximum allowable rotation speed of the roller screw, reducing the noise generated during the operation of the roller screw, and the output lead is not affected by the nut load, the screw rod rotation speed and the pre-tightening force.

[0022] In the scheme 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 with the two ends of the planetary retainer, the second roller is arranged between the outer sleeve and the second nut along the radial direction of the second nut, the second roller includes a second roller threaded area, the second roller threaded area is engaged with a partial area of the outer sleeve, the partial area of the outer sleeve engaged with the second roller threaded area has the same pitch, the same helix angle and the opposite helix line of the second roller threaded area, compared with the way of using the helix angle of 0 and the roller and nut with ring tooth structure in the differential planetary roller screw in the related art, since the partial area of the outer sleeve engaged with the second roller threaded area has the same pitch, the same helix angle and the opposite helix line of the second roller threaded area, a constant output lead far smaller than the screw thread lead is functionally realized, so that the application range of the micro-lead differential planetary roller screw is widened to the micro-lead field; moreover, the second coupling structure is arranged between the second roller and the outer sleeve, so that the second roller and the second nut are coupled in structure, the second coupling structure can keep the axis of the second roller and the outer sleeve always parallel, the second roller does not tilt, so that the ratio of the rotational speed of the second roller to the orbital speed and the ratio of the orbital speed of the second roller to the rotational speed of the second nut are constant values, thereby improving the service life and the maximum allowable rotational speed of the roller screw, and the noise generated in the operation of the roller screw can also be reduced, and the output lead is not affected by the nut load, the screw rotational speed and the pre-tightening force.

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0025] FIG. 1 shows a cross-sectional view of a micro-lead differential planetary screw provided by the embodiment 1 of the present application;

[0026] FIG. 2 shows a left view of the micro-lead differential planetary screw provided by the embodiment of the present application;

[0027] FIG. 3 shows a partial enlarged view of FIG. 1A provided by the embodiment of the present application;

[0028] Fig. 4 shows a perspective structural schematic diagram of a first retainer provided by an embodiment of the application;

[0029] Fig. 5 shows a perspective structural schematic diagram of a second retainer provided by an embodiment of the application;

[0030] Fig. 6 shows a structural schematic diagram of a micro-lead screw provided by an embodiment of the application;

[0031] Fig. 7 shows a sectional view of another micro-lead differential planetary roller screw provided by an embodiment of the application;

[0032] Fig. 8 shows a structural schematic diagram of another micro-lead screw provided by an embodiment of the application. DETAILED DESCRIPTION

[0033] In the description of the present application, it needs to 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" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0034] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0035] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0036] The rollers and nuts used in the differential planetary roller screw have a helix angle of 0 and a ring tooth structure. Such a structure will produce a differential effect to reduce the lead of the assembly, but the differential effect is limited, and can only reduce the lead to the millimeter level, but cannot reduce the lead to within one hundred microns.

[0037] Based on this, the following embodiments of the application propose a micro lead differential planetary roller screw and an electric cylinder. Since the design of the part of the screw rod engaged with the first roller thread area is the same as the pitch of the first roller thread area, the helix angle is equal, and the helical line is opposite in rotation, or since the design of the part of the outer sleeve engaged with the second roller thread area is the same as the pitch of the second roller thread area, the helix angle is equal, and the helical line is opposite in rotation, the constant output lead that is much smaller than the screw thread lead is achieved in function, so that the application range of the micro lead differential planetary roller screw is widened to the micro lead field. Moreover, the first coupling structure between the first roller and the screw rod enables the coupling of the first roller and the first nut in structure, so that the first roller does not slide during rotation, and the ratio of the first roller's rotational speed to the orbital speed and the ratio of the first roller's orbital speed to the first nut's rotational speed are both constant values, thereby improving the service life and the maximum allowable rotational speed of the roller screw.

[0038] In the following embodiments, the term "micro lead" refers to a lead of tens of microns to about one hundred microns.

[0039] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the drawings and embodiments.

[0040] Embodiment 1

[0041] Referring to the cross-sectional view of the micro lead differential planetary screw shown in FIG. 1, the left view of the micro lead differential planetary screw shown in FIG. 2, the partial enlarged view of FIG. 1A shown in FIG. 3, the perspective structural schematic view of the first retainer shown in FIG. 4, and the perspective structural schematic view of the second retainer shown in FIG. 5, the present embodiment proposes a micro lead differential planetary roller screw, which comprises an outer shell 4, a screw rod 1, a first roller 2, a first nut 3, a first bearing 6, an end cover 5, a first retainer 7, a second retainer 8, and a first coupling structure 9 arranged in the outer shell 4.

[0042] The end cover 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 rod 1, the outer shell 4 is sleeved on the first nut 3, the end cover 5 is fixed at both ends of the outer shell 4, the first bearing 6 is arranged between the end cover 5 and the first nut 3, and both ends of the first nut 3 are connected to the end faces of the end cover 5 facing the first nut 3 through the first bearing 6.

[0044] The screw 1 and the shell 4 are respectively connected with the outside. The screw 1 is connected with a driven body, and the shell 4 is fixedly connected with the outside to fix the micro lead differential planetary screw.

[0045] Specifically, the number of the first bearings 6 is two, and each of the first bearings 6 is a bearing capable of bearing unidirectional axial load, or at least one of the first bearings 6 is a four-point contact ball bearing capable of bearing bidirectional axial load.

[0046] The bearing capable of bearing unidirectional axial load can be, but is not limited to, an angular contact bearing, a thrust ball bearing, and a cylindrical roller bearing.

[0047] The first retainer 7 and the second retainer 8 are respectively sleeved on both sides of the screw 1, the first retainer 7 is rotationally connected with the end cover 5 located at one end of the shell 4, and the second retainer 8 is rotationally connected with the end cover 5 located at the other side of the shell 4.

[0048] Specifically, the first retainer 7 is provided with a through hole 701 in the middle, and the second retainer 8 is provided with 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 an embodiment, the axes of the screw 1, the first nut 3, and the shell 4 coincide.

[0050] Both ends of the first roller 2 are respectively rotationally connected with the first retainer 7 and the second retainer 8; the first roller 2 is arranged between the screw 1 and the first nut 3 along the radial direction of the screw 1; the first roller 2 comprises a first roller threaded area 201 and a first roller ring gear area 202, the first roller threaded area 201 is engaged with a part of the screw 1, and the first roller ring gear area 202 is in contact with a part of the first nut 3; wherein the part of the screw 1 engaged with the first roller threaded area 201 has the same pitch, equal helix angle, and opposite helix line direction as the first roller threaded area 201; and the part of the first nut 3 in contact with the first roller ring gear area 202 is a ring groove structure. The number of the first rollers 2 is multiple.

[0051] The first coupling structure 9 is fixedly connected with the shell 4 and the first roller 2, and rotationally connected with the first retainer 7.

[0052] After the rotation of the second retainer 8, the first roller 2 is driven to revolve around the screw rod 1. Since the screw thread area 101 of the screw rod 1 is engaged with the first roller thread area 201, the first roller 2 is also driven to rotate, so that the application range of the micro-lead differential planetary roller screw is extended to the micro-lead field.

[0053] The first retainer 7 and the second retainer 8 are respectively mounted on the inner annular side wall of the end cover 5 through 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. The outer diameter of the first roller thread area 201 is greater than the outer diameter of the first roller ring tooth area 202. The outer side wall of the screw rod 1 is provided with a screw rod thread area 101 engaged with the first roller thread area. The inner side wall of the first nut 3 is provided with a nut ring tooth area 301 at both ends, which is in contact with the first roller ring tooth area 202. Between the nut ring tooth area 301 at both ends of the first nut 3, a first ring wall area 302 is arranged on the inner side wall of the first nut 3, which is opposite to the first roller thread area 201. The first roller thread area 201 is not in contact with the first ring wall area 302, and the first roller ring tooth area 202 is not in contact with the screw rod thread area 101.

[0055] The screw rod thread area 101 is a part of the screw rod 1 engaged with the first roller thread area 201.

[0056] The nut ring tooth area 301 is a part of the first nut 3 in contact with the first roller ring tooth area 202.

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

[0058] The structure of the second retainer 8 is similar to that of the first retainer 7, which will not be described here.

[0059] The end of the first retainer 703 rotationally connected with the first roller 2 is provided with a first retainer mounting hole 702, and the end of the second retainer 8 rotationally connected with the first roller 2 is provided with a second retainer mounting hole 802. The two ends of the first roller 2 are respectively rotationally connected with the first retainer mounting hole 702 and the second retainer mounting hole 802 through bearings.

[0060] Here, the number of the first mounting posts 703 corresponds to the number of the first retainer mounting holes 702 and the positions correspond.

[0061] The first retainer 7 and the second retainer 8 are mounted on the inner side wall of the end cover 5 by rotating through the first bearings (not shown in the figure), and the two ends of the first roller 2 are mounted in the first retainer mounting holes 702 and the second retainer mounting holes 802 by rotating through the first bearings (not shown in the figure).

[0062] In one embodiment, the first retainer mounting holes 702 and the second retainer mounting holes 802 are respectively arranged symmetrically about the axis center 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] As shown in FIG. 2, in one embodiment, the first coupling structure 9 includes an inner ring gear 901, a first gear 902, and a second gear 903.

[0065] The inner ring gear 901 is fixedly connected to the inner wall of the housing 4, the second gear 903 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 is meshed with the corresponding second gear 903, and the second gear 903 is also meshed with the inner ring gear 901. The second gear 903 mainly changes the transmission direction, making it possible for the first coupling structure to rotate, so that the ratio of the roller's rotational speed to its orbital speed and the ratio of the roller's orbital speed to the nut's rotational speed are constant values.

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

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

[0068] Optionally, in the case of the second gear 903 employing a multi-stage gear, the first coupling structure 9 described above can further include: the inner ring gear 901, the first gear 902 and the multi-stage gear; the inner ring gear 901 is fixedly connected to the inner wall of the shell 4; the multi-stage gear is rotatably connected to the first mounting column 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 is respectively engaged with the last stage gear of the corresponding multi-stage gear 903, and the first stage gear of the multi-stage gear is engaged with the inner ring gear 901. The second gear 903 employing a multi-stage gear mainly changes the transmission direction, so that the first coupling structure can rotate, thereby the ratio of the rotational speed of the roller to the orbital speed, and the ratio of the orbital speed of the roller to the rotational speed of the nut are constant values.

[0069] Referring to the structural diagram of a micro-lead screw shown in FIG. 6, the present embodiment proposes a micro-lead screw, which comprises the micro-lead differential planetary roller screw, a connecting shaft 10 and an actuator 11; wherein the other end of the second retainer 8 of the micro-lead differential planetary roller screw extends out of the end cover 5, the connecting shaft 10 is a barrel with one end sealed and one end open, the open end of the connecting shaft 10 is fixedly connected to the extended end of the second retainer 8, and 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 formed in the sidewall of the extended end of the second retainer 8, a second threaded hole 1001 is formed in the sidewall of the open end of the connecting shaft 10, and the first threaded hole 803 and the second threaded hole 1001 are connected by a bolt 12.

[0071] In one embodiment, the actuator 11 can employ, but is not limited to, a brush motor and a brushless motor.

[0072] In operation: the screw rod 1 and the shell 4 are respectively fixedly connected to the outside, the actuator 11 drives the second retainer 8 to rotate, under the action of the second retainer 8, the first roller 2 will revolve around the screw rod 1, and since the screw rod thread area 101 of the screw rod 1 is engaged with the first roller thread area 201, the first roller 2 will also rotate, thereby widening the application range to the micro-lead field.

[0073] In the process of rotating the first roller 2, the first gear 902 fixedly connected to the first roller 2 will rotate, thereby driving the multi-stage gear 903 engaged with the first gear 902 to rotate, and the multi-stage gear 903 will revolve around the inner ring gear 901, thereby maintaining the positional relationship between the first roller 2 and the shell 4, which will not be tilted due to sliding, and since the screw rod 1 and the shell 4 are respectively fixedly connected to the outside, no sliding occurs between the first roller 2 and the shell 4, i.e. no sliding occurs between the first roller 2 and the screw rod 1.

[0074] The micro lead differential planetary roller screw and the micro lead electric cylinder have the following characteristics:

[0075] In the micro lead differential planetary roller screw and the electric cylinder, when the screw is subjected to an axial load, the load is transmitted from the screw to the first roller, then from the first roller to the first nut, then the first nut transmits the load to the first bearing, and finally the first bearing transmits the load to the shell. 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 friction force generated at the meshing position of the first roller and the first nut in the circumferential direction, further reducing the friction force, improving the transmission efficiency of the system, reducing the noise generated during the operation of the first roller and the screw, and improving the service life and maximum allowable rotation speed of the electric cylinder.

[0076] In summary, the micro lead differential planetary roller screw and the micro lead electric cylinder have the following characteristics: in the micro lead differential planetary roller screw, the two ends of the first roller are rotatably connected to the first retainer and the second retainer, respectively, and the first roller is arranged between the screw and the first nut in the radial direction of the screw. The first roller thread area in the first roller is engaged with a part of the screw, and the part of the screw engaged with the first roller thread area has the same pitch, equal helix angle, and opposite helix direction as the first roller thread area. Compared with the related art, in which the helix angle of the screw thread is 0 and the roller and nut have a ring tooth structure, the design of the part of the screw engaged with the first roller thread area having the same pitch, equal helix angle, and opposite helix direction as the first roller thread area achieves a constant output lead that is much smaller than the screw thread lead, which widens the application range of the micro lead differential planetary roller screw to the micro lead field. Moreover, the first coupling structure between the first roller and the screw enables the first roller and the first nut to be coupled in structure, and the first coupling structure can keep the axes of the first roller and the screw parallel at all times, so that the first roller does not tilt, and the ratio of the first roller's rotational speed to its orbital speed and the ratio of the first roller's orbital speed to the first nut's rotational speed are both constant values, thereby improving the service life and maximum allowable rotation speed of the roller screw, reducing the noise generated during the operation of the roller screw, and making the output lead unaffected by the load of the nut, the rotation speed of the screw, and the pre-tightening force.

[0077] Example 2

[0078] Referring to the cross-sectional view of another micro-lead differential planetary roller screw shown in Figure 7, this embodiment proposes a micro-lead differential planetary roller screw, including: a smooth 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 further comprises a linear sensor i; the spline shaft g02 is provided with a mounting hole g021 coaxial with the spline shaft g02.

[0087] The linear sensor i comprises a grating ruler i01, a reading head i02 and a mounting plate i03; the grating ruler i01 is arranged in the mounting hole g021, the mounting plate i03 is arranged in the spline hole a01 and fixed at one end of the light rod a, and the reading head i02 is arranged on the mounting plate i03. The reading head i02 can obtain data of position change on the grating ruler i01 and is electrically connected with a data processing device.

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

[0089] The micro lead differential planetary roller screw further comprises a linear sensor i; the spline shaft g02 is provided with a mounting hole g021 coaxial with the spline shaft g02.

[0090] The inner side wall of the outer sleeve g is provided with an outer sleeve thread area g01 engaged with the second roller thread area b01; the outer side wall of the second nut c is provided with a second nut ring tooth area b02 at both ends thereof and in contact with the second roller ring tooth area b02, and the outer side wall of the second nut c is further provided with a second ring wall area c02 arranged opposite to the second roller thread area b01 between the second nut ring tooth areas b02 at both ends of the second nut c; wherein the second roller thread area b01 is not in contact with the second ring wall area c02, and the second roller ring tooth area b02 is not in contact with the outer sleeve thread area g01.

[0091] The two ends of the planetary retainer d rotatably connected with the second roller b are respectively provided with mounting holes, and the two ends of the second roller are rotatably connected with the mounting holes at the two ends of the planetary retainer through bearings.

[0092] The second mounting column d01 is arranged at one end of the planetary retainer d away from the second nut b; and the end of the second roller b away from the second nut c is extended outward to form a second extension.

[0093] The second coupling structure f comprises a third gear f01, a fourth gear f02 and a fifth gear f03; the third gear f01 is fixedly connected with the outer wall of the polished rod a; the fourth gear f02 is rotationally connected with the second mounting column d01; the fifth gear f03 is fixedly connected with the second extension of the second roller b; the fourth gear f02 is engaged with the corresponding fifth gear f03 and the fourth gear f02 is also engaged with the third gear f01. The fourth gear f02 mainly changes the transmission direction, so that the second coupling structure f can rotate, and the ratio of the rotational speed of the second roller b to the orbital speed, the orbital speed of the second roller b and the rotational speed of the second nut c are constant values.

[0094] Optionally, a bearing spacing ring j is arranged between the polished rod a and the second nut c, and the two ends of the bearing spacing ring j are respectively abutted against the second bearing e. The arrangement of the bearing spacing ring j facilitates the transmission of the load and makes the structure more stable.

[0095] Referring to another structure diagram of the micro-lead screw electric cylinder shown in FIG. 8, the micro-lead screw electric cylinder comprises the micro-lead differential planetary roller screw, the shaft coupling h and the actuator 11. The actuator 11 is fixedly connected with the planetary holder d through the shaft coupling h, and the inner diameter of the outer sleeve g is greater than the outer diameter of the actuator 11.

[0096] The outer sleeve g and the actuator 11 are respectively fixedly connected with the outside; the outer sleeve g is connected with the driven object; and the actuator 11 is fixedly connected with the outside to fix the micro-lead differential planetary screw.

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

[0098] In the process of rotating the second roller b, the fifth gear f03 fixedly connected with the second roller b will rotate, thereby driving the fourth gear f02 engaged with the fifth gear f03 to rotate, and the fourth gear f02 will rotate around the third gear f01, thereby keeping the positional relationship between the second roller b and the polished rod a from being inclined due to sliding. Since the polished rod a and the outer sleeve g do not rotate, the second roller b and the polished rod a do not slide, that is, the second roller b and the outer sleeve g do not slide.

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

[0100] 1. Micro small lead differential planetary roller screw and electric cylinder, when the outer sleeve is subjected to axial load during operation, the load is transmitted from the outer sleeve to the second roller, then from the second roller to the second nut, then the second nut transmits the load to the second bearing, and finally the second bearing transmits the load to the polished rod. The structural features not only improve the axial load capacity of the system, but also allow the second nut to rotate freely around the second bearing during system operation. The rotation of the second bearing disperses the friction force generated at the meshing position of the second roller and the second nut in the circumferential direction, further reducing the friction force, improving the transmission efficiency of the system, reducing the noise generated during the operation of the second roller and the outer sleeve, and improving the service life and maximum allowable rotation speed of the electric cylinder.

[0101] 2. Micro small lead differential planetary roller screw and electric cylinder, the linear sensor can accurately and effectively position the electric cylinder during positioning. The data processing device can determine the position state of the outer sleeve according to the position information measured by the linear sensor, ensuring the stability and reliability of the electric cylinder in operation. The structure is compact, easy to install and use, high in automation, safe and reliable, and compared with related technologies, the detection method does not have angle back difference, effectively reduces the deviation between the determined position of the outer sleeve and the actual position of the outer sleeve, and improves the control accuracy.

[0102] In summary, the embodiment provides 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 retainer, the second roller is arranged between the outer sleeve and the second nut along the radial direction of the second nut, the second roller includes a second roller threaded area, the second roller threaded area is engaged with a partial area of the outer sleeve, the partial area of the outer sleeve engaged with the second roller threaded area has the same pitch, equal helix angle and opposite helix line direction as the second roller threaded area. Compared with the related art in which the helix angle of the screw thread used in the differential planetary roller screw is 0 and the roller and the nut are ring tooth structure, the partial area of the outer sleeve engaged with the second roller threaded area has the same pitch, equal helix angle and opposite helix line direction as the second roller threaded area, which functionally realizes a constant output lead that is much smaller than the screw thread lead of the screw rod, so that the application range of the micro-lead differential planetary roller screw is widened to the micro-lead field. Moreover, the second coupling structure is arranged between the second roller and the outer sleeve, so that the second roller and the second nut are structurally coupled, the second roller and the outer sleeve do not slide during rotation, the second coupling structure can keep the axes of the second roller and the outer sleeve always parallel, the second roller does not tilt, the ratio of the rotational speed of the second roller to the orbital speed, and the ratio of the orbital speed of the second roller to the rotational speed of the second nut are constant values, thereby improving the service life and the maximum allowable rotational speed of the roller screw, reducing the noise generated during the operation of the roller screw, and the output lead is not affected by the load of the nut, the rotational speed of the screw rod and the pre-tightening force.

[0103] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A fine pitch differential planetary roller screw characterized by, The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw.

2. The fine pitch differential planetary roller screw of claim 1 wherein, The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw.

3. The fine pitch differential planetary roller screw of claim 1 wherein, The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. The application relates to a micro-lead differential planetary roller screw. 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The application relates to a micro-lead differential planetary roller screw. The application relates to a micro- The first end of the first cage rotatably connected with the first roller is provided with a first cage mounting hole, and the first end of the second cage rotatably connected with the first roller is provided with a second cage mounting hole; the two ends of the first roller are rotatably connected with the first cage mounting hole and the second cage mounting hole through bearings respectively; The end of the first roller located in the first cage mounting hole extends outward to form a first extension.

4. The fine pitch differential planetary roller screw of claim 3 wherein, The first coupling structure comprises an inner ring, a first gear and a second gear; The inner ring is fixedly connected with the inner wall of the shell; The second gear is rotatably connected with the first mounting column, the first gear is fixedly connected with the first extension formed at the end of the first roller, the first gear is meshed with the corresponding second gear, and the second gear is also meshed with the inner ring.

5. A fine pitch differential planetary roller screw characterized by, It comprises: an optical rod, a second roller, a second nut, a planetary cage, a second bearing, a second coupling structure and an outer sleeve; The second nut is sleeved on the optical rod, the planetary cage is sleeved on both sides of the second nut, the second nut is located in the planetary cage, the planetary cage is rotatably connected with the optical rod, the second nut and the optical rod are rotatably connected through the second bearing, and the outer sleeve is sleeved on the planetary cage; The two ends of the second roller are rotatably connected with the two ends of the planetary cage respectively; The second roller is arranged between the outer sleeve and the second nut along the radial direction of the second nut; The second roller comprises a second roller threaded area and a second roller ring gear area, the second roller threaded area is meshed with part of the area of the outer sleeve, and the second roller ring gear area is in contact with part of the area of the second nut; wherein the part of the area of the outer sleeve meshed with the second roller threaded area has the same pitch, equal helix angle and opposite helical line rotation direction as the second roller threaded area; the part of the area of the second nut in contact with the second roller ring gear area is also a ring groove structure; The second coupling structure is fixedly connected with the optical rod and the second roller respectively, and is rotatably connected with the planetary cage; After the rotation of the cage, the second roller revolves around the second nut, and since the second roller threaded area is meshed with part of the area of the outer sleeve, the second roller also rotates, thereby widening the application range of the micro-lead differential planetary roller screw to the micro-lead field.

6. The fine pitch differential planetary roller screw of claim 5, wherein, It further comprises: a spline shaft; A spline hole is formed in the optical rod, the spline hole is coaxial with the optical rod, the spline shaft is inserted into the spline hole, the spline shaft can move in the spline hole, and the rotation of the optical rod around its own axis is limited.

7. The fine pitch differential planetary roller screw of claim 5 wherein, It further comprises: a linear sensor; An installation hole is also formed in the spline shaft, and the installation hole is coaxial with the spline shaft; The linear sensor comprises a grating ruler, a reading head and a mounting plate; The grating ruler is arranged in the installation hole, the mounting plate is located in the spline hole and one end of the mounting plate is fixed on the optical rod, and the reading head is mounted on the mounting plate.

8. The fine pitch differential planetary roller screw of claim 5 wherein, The second roller thread region is located in the middle of the second roller, and the second roller ring tooth region is located on both sides of the second roller; wherein the outer diameter of the second roller thread region is greater than the outer diameter of the second roller ring tooth region; The inner side wall of the outer sleeve is provided with an outer sleeve thread region engaged with the second roller thread region; the outer side wall of the second nut is provided with a second nut ring tooth region at both ends thereof in contact with the second roller ring tooth region, and a second ring wall region is further provided on the outer side wall of the second nut between the second nut ring tooth regions at both ends thereof and arranged opposite to the second roller thread region; wherein the second roller thread region is not in contact with the second ring wall region, and the second roller ring tooth region is not in contact with the outer sleeve thread region.

9. The fine pitch differential planetary roller screw as set forth in claim 5, wherein, Both ends of the planetary retainer rotationally connected with the second roller are respectively provided with mounting holes, and both ends of the second roller are respectively rotationally connected with the mounting holes at both ends of the planetary retainer through bearings; An end of the planetary retainer away from the second nut is provided with a second mounting column; The end of the second roller located at the end of the planetary retainer away from the second nut is outwardly extended to form a second extension; The second coupling structure comprises a third gear, a fourth gear and a fifth gear; The third gear is fixedly connected with the outer wall of the polished rod, the fourth gear is rotationally connected with the second mounting column, the fifth gear is fixedly connected with the second extension of the end of the second roller, the fourth gear is engaged with the corresponding fifth gear, and the fourth gear is further engaged with the third gear.

10. A micro-lead electrical cylinder characterized in that, The method comprises: The micropitch differential planetary roller screw according to any one of claims 1-4 or any one of claims 5-9.

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