Sectional type planetary roller lead screw pair

Abstract

A sectional type planetary roller lead screw pair comprises a lead screw, a nut and a plurality of rollers, the lead screw is arranged in the nut in a penetrating mode and coincides with the axis of the nut, inner gear rings are arranged on the inner sides of the two ends of the nut, and the two ends of the rollers are evenly distributed between the lead screw and the nut through retainers in the circumferential direction of the lead screw respectively. Tooth sections meshed with the corresponding inner gear rings are arranged at the two ends of the pin roller respectively, a plurality of small-diameter thread sections meshed with the nut are arranged between the tooth sections on the pin roller, and a plurality of large-diameter thread sections meshed with the lead screw are arranged between the tooth sections on the pin roller. According to the segmented planetary roller lead screw pair, the small-diameter thread sections on the rollers are meshed with the nut thread areas, the large-diameter thread sections on the rollers are meshed with the lead screw threads, the maximum contact force of the thread teeth is remarkably reduced in the actual use process of the whole segmented planetary roller lead screw pair, then the bearing capacity of the planetary roller lead screw pair is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of transmission devices, and particularly relates to a segmented planetary roller screw pair. Background Art

[0002] A planetary roller screw pair is a mechanical transmission device that can convert rotational motion and linear motion into each other, and is composed of a screw, a nut, rolling elements, a planetary carrier, an internal gear ring, etc. The rolling elements of the planetary roller screw pair are planetary rollers. Compared with the commonly used ball screw pair, the planetary roller screw pair has the transmission characteristics of multiple points, multiple pairs, and multiple bodies, which determines its advantages of large thrust, high precision, high rigidity, long service life, good dynamic performance, convenient installation and maintenance, etc.

[0003] At present, under the action of a large load, the traditional planetary roller screw pair will generate large contact stress and contact deformation at the thread meshing positions of the screw and the roller, and between the roller and the nut near the stress side, thus reducing the load-bearing capacity and service life of the roller screw. Summary of the Invention

[0004] To overcome the deficiencies of the prior art, the present invention proposes a segmented planetary roller screw pair, which significantly reduces the maximum contact force of the thread teeth during actual use, thereby improving the load-bearing capacity of the planetary roller screw pair and increasing the service life.

[0005] The technical solution adopted by the present invention is:

[0006] A segmented planetary roller screw pair includes a screw, a nut, and a plurality of rollers. The screw is disposed through the nut and coincides with the axis of the nut. Inner gear rings are provided on the inner sides of both ends of the nut. The two ends of the rollers are respectively installed between the screw and the nut along the circumferential direction of the screw through a cage. Tooth sections meshing with the corresponding inner gear rings are respectively provided at the two ends of the rollers. A plurality of small-diameter thread sections meshing with the nut are provided on the rollers between the tooth sections. A plurality of large-diameter thread sections meshing with the screw are provided on the rollers between the tooth sections.

[0007] Further, the nut has a hollow cavity. A threaded area is provided in the hollow cavity corresponding to the position of the small-diameter thread sections. An annular wall area is provided in the hollow cavity corresponding to the position of the large-diameter thread sections. The inner diameter of the threaded area is smaller than the inner diameter of the annular wall area.

[0008] Further, no thread is provided in the annular wall area.

[0009] Further, the two ends of the roller are smooth shaft sections that are installed in cooperation with the cage and rotate relative to each other.

[0010] Further, the small-diameter thread sections are arranged at intervals.

[0011] Further, the diameter of the tooth segment is equal to the diameter of the small-diameter thread segment and neither of them meshes with the lead screw thread.

[0012] Further, large-diameter thread segments are provided between adjacent small-diameter thread segments.

[0013] Further, the diameter of the large-diameter thread segment is larger than the diameter of the small-diameter thread segment, and the large-diameter thread segment does not mesh with the nut thread.

[0014] Further, the cage is positioned and installed in the internal gear ring through a circlip.

[0015] The beneficial effects of the present invention: By making the small-diameter thread segments on the rollers mesh with the nut thread area and the large-diameter thread segments mesh with the lead screw thread, the maximum contact force of the thread teeth of the overall segmented planetary roller screw pair is significantly reduced during actual use, thereby improving the load-bearing capacity of the planetary roller screw pair and increasing the service life. Description of the Drawings

[0016] Figure 1 is a three-dimensional structural schematic diagram of the present invention;

[0017] Figure 2 is a sectional structural schematic diagram of the present invention;

[0018] Figure 3 is a structural schematic diagram of the roller of the present invention;

[0019] Figure 4 is a sectional structural schematic diagram of the nut of the present invention.

[0020] In the figure: 1, lead screw; 2, circlip; 3, cage; 4, internal gear ring; 5, nut; 51, first thread area; 52, first annular wall area; 53, second thread area; 54, second annular wall area; 55, third thread area; 6, roller; 61, smooth shaft section; 62, tooth segment; 63, first small-diameter thread segment; 64, first large-diameter thread segment; 65, second small-diameter thread segment; 66, second large-diameter thread segment; 67, third small-diameter thread segment. Detailed Embodiments

[0021] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternative solutions, improvement solutions, and equivalent solutions that may be included within the scope of the claims.

[0022] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more, unless otherwise clearly defined.

[0023] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0025] See Figures 1-4, this embodiment provides a segmented planetary roller screw pair, including a screw 1, a nut 5, and several rollers 6. The screw 1 is inserted into the nut 5 and coincides with the axis of the nut 5. Inner gear rings 4 are provided on the inner sides of both ends of the nut 5. The two ends of the roller 6 are respectively installed between the screw 1 and the nut 5 along the circumferential direction of the screw 1 through a cage 3, and the cage 3 is positioned and installed in the inner gear ring 4 through a snap ring 2. The cage 3 is used to maintain the position of the roller 6 during movement, and the snap ring 2 is clamped at the groove of the inner gear ring 4 to limit the axial displacement of the cage 3.

[0026] In this embodiment, the two ends of the roller 6 are smooth shaft sections 61 that are fitted and rotatable relative to the cage 3. Tooth sections 62 that mesh with the corresponding inner gear rings 4 are provided on the inner sides of the two ends of the roller 6 in the smooth shaft sections 61. Several small-diameter thread sections that mesh with the nut 5 are provided between the tooth sections 62 on the roller 6, and several large-diameter thread sections that mesh with the screw 1 are provided between the tooth sections 62 on the roller 6.

[0027] In this embodiment, the small-diameter thread sections are arranged at intervals, including a first small-diameter thread section 63, a second small-diameter thread section 65, and a third small-diameter thread section 67. The diameter of the tooth section 62 is equal to that of the small-diameter thread section and does not mesh with the screw thread. Large-diameter thread sections are provided between adjacent small-diameter thread sections, including a first large-diameter thread section 64 and a second large-diameter thread section 66. The diameter of the large-diameter thread section is larger than that of the small-diameter thread section, and the large-diameter thread section does not mesh with the nut thread. Specifically, the tooth section 62 forms a mesh with the inner gear ring 4 and does not mesh with the screw 1 thread. The first small-diameter thread section 63 meshes with the first nut thread area 51, the second small-diameter thread section 65 meshes with the second nut thread area 53, the third small-diameter thread section 67 meshes with the third nut thread area 55, and the first large-diameter thread section 64 and the second large-diameter thread section 66 mesh with the screw 1 thread. The helix directions and pitches of the first small-diameter thread section 63, the second small-diameter thread section 65, and the third small-diameter thread section 67 of the roller 6 in this embodiment are the same, the number of threads of the first small-diameter thread section 63 and the third small-diameter thread section 67 is the same, the number of threads of the second small-diameter thread section 65 is more than that of the first small-diameter thread section 63 and the third small-diameter thread section 67, and the helix directions, pitches, and the number of threads of the first large-diameter thread section 64 and the second large-diameter thread section 66 of the roller 6 are also the same.

[0028] The nut 5 in this embodiment has a hollow cavity. A threaded area is provided at a position corresponding to the small-diameter threaded section in the hollow cavity, and an annular wall area is provided at a position corresponding to the large-diameter threaded section in the hollow cavity. The inner diameter of the threaded area is smaller than that of the annular wall area, and no threads are provided in the annular wall area. Specifically, corresponding to the arrangement of the rollers 6, the hollow cavity of the nut 5 axially forms a first threaded area 51, a second threaded area 53, a third threaded area 55, a first annular wall area 52, and a second annular wall area 54. Each threaded area corresponds to the small-diameter threaded section of the roller 6, and each annular wall area corresponds to the large-diameter threaded section of the roller 6.

[0029] The lead screw 1 in this embodiment has an external thread that can mesh with the large-diameter threaded section.

[0030] During use, power is input through the lead screw 1. One end of the lead screw 1 is connected to a motor, and the output of the movement is connected to an actuator through the nut 5. The motor drives the lead screw 1 to rotate. The thread of the lead screw 1 meshes with the thread of the roller 6. The frictional force and the meshing force drive the roller 6 to rotate around its own axis. Since the nut 5 is restricted, at the same time, the planetary roller 6 makes a revolution in the same direction. The revolution movement of the roller 6 pushes the nut 5 to translate along the axis direction of the lead screw 1, thereby realizing the linear movement of the nut 5.

[0031] In the present invention, the small-diameter threaded section on the roller meshes with the threaded area of the nut, and the large-diameter threaded section meshes with the thread of the lead screw. While converting the rotational movement into a linear movement, the maximum contact force of the thread teeth of the overall segmented planetary roller screw pair is significantly reduced during actual use, thereby improving the load-bearing capacity of the planetary roller screw pair and increasing the service life.

[0032] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the concept of the present invention by using the content of the specification and drawings of the present invention, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A segmented planetary roller screw pair, comprising a screw rod, a nut, and a plurality of rollers. The screw rod is disposed within the nut and coincides with the axis of the nut. Inner gear rings are provided on the inner sides of both ends of the nut. The two ends of each roller are respectively installed between the screw rod and the nut along the circumferential direction of the screw rod through a cage, and are evenly distributed. It is characterized in that: Both ends of the roller are respectively provided with tooth sections meshing with the corresponding internal gear rings. A number of small-diameter threaded sections meshing with the nut are arranged on the roller between the tooth sections, and a number of large-diameter threaded sections meshing with the lead screw are arranged on the roller between the tooth sections.

2. The segmented planetary roller screw pair according to claim 1, characterized in that: The nut has a hollow cavity. A threaded area is arranged at a position corresponding to the small-diameter threaded section in the hollow cavity, and an annular wall area is arranged at a position corresponding to the large-diameter threaded section in the hollow cavity. The inner diameter of the threaded area is smaller than the inner diameter of the annular wall area.

3. The segmented planetary roller screw pair according to claim 2, wherein: No threads are provided in the annular wall area.

4. A segmented planetary roller screw pair according to claim 1, characterized in that: Both ends of the roller are smooth shaft sections that are installed in cooperation with the cage and rotate relative to each other.

5. A segmented planetary roller screw pair according to claim 1, characterized in that: The small-diameter threaded sections are arranged at intervals.

6. A segmented planetary roller screw pair according to claim 5, characterized in that: The diameter of the tooth section is equal to the diameter of the small-diameter threaded section and neither of them meshes with the lead screw thread.

7. A segmented planetary roller screw pair according to claim 5, characterized in that: A large-diameter threaded section is arranged between adjacent small-diameter threaded sections.

8. A segmented planetary roller screw pair according to claim 7, characterized in that: The diameter of the large-diameter threaded section is larger than the diameter of the small-diameter threaded section, and the large-diameter threaded section does not mesh with the nut thread.

9. A segmented planetary roller screw pair according to claim 1, characterized in that: The cage is positioned and installed in the internal gear ring through a circlip.

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