Planetary roller screw drive

Abstract

In order to solve the problem that the machining difficulty of the large length-diameter ratio nut and roller of the existing anti-type planetary roller screw product is too large, the application provides a planetary roller screw transmission device, the outer thread length of the roller 2 is larger than the inner thread length of the nut 1 and the outer thread length of the screw 3. The thread length of the nut 1 can be shorter than 3 cm, and the length-diameter ratio of the nut can be smaller than 2, which greatly reduces the machining difficulty. Because the inner thread 11 of the nut with a short length or the outer thread 31 of the screw only moves between the retainer 4 of the roller set 200, the two ends of the roller 2 can adopt the externally mounted tooth type complete planetary gear 24, and the integral machining with the roller 2 is not needed. The application significantly reduces the machining difficulty of such products, and creates favorable conditions for low-cost implementation.

Description

Technical Field

[0001] This invention relates to lead screw transmission devices, and more particularly to planetary roller lead screw transmission devices. Background Technology

[0002] Existing electric push rod transmission products that utilize reverse roller screw technology have the following two well-known technical defects:

[0003] 1. In order to ensure both a sufficiently long working stroke and a sufficiently large load-bearing capacity, the length-to-diameter ratio of the nut must be very large, even greater than 10:1. However, the thread machining of high-precision nuts with large length-to-diameter ratios is extremely difficult, time-consuming, inefficient, and has a low yield rate, which is the main obstacle restricting the low-cost manufacturing of such products.

[0004] 2. Due to its inherent limitations, the length of its roller thread must be much shorter than the thread length of the nut. Technically, the pitch diameter of the roller thread must be the same as the pitch circle of the planetary gear. Therefore, the gear portion of the roller needs to mesh with both the gear on the internal gear ring and the thread of the leadscrew. This results in a combination of gears and threads at both ends of the roller, creating a complex gear-threaded section. While this structure ensures no interference between the planetary gear and the thread, guaranteeing normal transmission of the planetary roller leadscrew, this complex structure is not only complex and difficult to manufacture, but also generates many difficult-to-clean burrs between the cross grooves of the gear teeth and the threads. Furthermore, the dense cutting of the gear teeth by the thread grooves leads to incomplete tooth profiles, reducing gear strength and increasing noise. Similarly, the presence of gears on the threads at both ends results in incomplete thread sections, affecting thread strength and further generating noise. Besides noise generation, the incomplete, discontinuous threads in the combined thread-gear section are more prone to wear, affecting the limiting and guiding function of the roller. Summary of the Invention

[0005] To address the aforementioned deficiencies in the prior art, the present invention proposes a planetary roller screw transmission device, comprising a nut 1, multiple rollers 2 inserted into the nut 1, and a screw 3 surrounded by the rollers 2; the external threads 21 of the rollers 2 engage with the external threads 31 of the screw 3 and with the internal threads 11 of the nut 1; and a ring-shaped retainer 4 is inserted into each end of the rollers 2.

[0006] Its uniqueness lies in:

[0007] The total length of the external thread 31 of the lead screw 3 is not greater than the total length of the external thread 21 of the roller 2;

[0008] The total length of the external thread 21 of the roller 2 is not less than the total length of the internal thread 11 of the nut 1;

[0009] The total length of the external thread 31 of the lead screw 3 is not equal to the total length of the internal thread 11 of the nut 1;

[0010] The difference between the total length of the external thread 31 of the lead screw 3 and the total length of the internal thread 11 of the nut 1 is approximately equal to the working stroke of the device;

[0011] When the device is running, the lead screw 3 and the nut 1 rotate relative to each other under the drive of the power mechanism;

[0012] When the device is running, the external thread 31 of the lead screw 3 and the internal thread 11 of the nut 1 are always located between the retainers 4 at both ends of the roller 2.

[0013] Preferably,

[0014] The device includes a main housing 5.

[0015] The left end of the nut 1 is fixedly connected to the right end of a nut extension tube 12;

[0016] The inner diameter of the cavity 122 of the nut extension tube is larger than the major diameter of the internal thread 11 of the nut;

[0017] The nut 1 and the nut extension tube 12 are circumferentially fixed relative to the main housing 5;

[0018] The thread direction of the roller 2 is opposite to that of the thread direction of the nut 1 and the lead screw 3;

[0019] The lead screw 3 is axially fixed relative to the main housing 5;

[0020] The left end 121 of the nut extension tube extends to the left from the left end hole 51 of the housing;

[0021] The total length of the internal thread 11 of the nut is less than the total length of the external thread 21 of the roller, and the difference is approximately equal to the working stroke of the device.

[0022] Preferably,

[0023] Each roller 2 has cylindrical end necks 22 at both ends, and each cylindrical end neck 22 is inserted into the inner hole of a circular end sleeve 23. The end sleeve 23 can be inserted into the retaining hole 41 of the same diameter of the retainer 4.

[0024] The retaining hole 41 has an outward notch 411, the width of which is less than the outer diameter of the end sleeve 23 and greater than the inner diameter of the end sleeve 23;

[0025] The cylindrical end neck 22 of each roller 2 passes through the inner hole of an end sleeve 23 and then through the middle hole of a planetary gear 24, and is fixedly connected to the planetary gear 24 in a detachable manner.

[0026] The pitch circle of planetary gear 24 is equal to the thread pitch diameter of roller 2;

[0027] The lead screw has sun gears 32 at both ends of its external thread 31, and each sun gear 32 meshes with a corresponding planetary gear 24.

[0028] When the device is running, the lead screw 3 rotates under the drive of the power mechanism and drives the nut extension tube 12 to move axially through the roller 2.

[0029] Preferably,

[0030] The device includes a main housing 5.

[0031] The nut 1 is axially fixed relative to the main housing 5;

[0032] The lead screw 3 is circumferentially fixed relative to the main housing 5;

[0033] The thread direction of the roller 2 is the same as that of the nut 1 and the lead screw 3;

[0034] The total length of the external thread 21 of the lead screw is less than the total length of the external thread 21 of the roller, and the difference is approximately equal to the working stroke of the device.

[0035] Preferably,

[0036] Each roller 2 has cylindrical end necks 22 at both ends, and each cylindrical end neck 22 is inserted into the inner hole of a circular end sleeve 23. The end sleeve 23 can be inserted into the retaining hole 41 of the same diameter of the retainer 4.

[0037] The retaining hole 41 has an inwardly facing notch 412, the width of which is less than the outer diameter of the end sleeve 23 and greater than the inner diameter of the end sleeve 23;

[0038] The cylindrical end neck 22 of each roller 2 passes through the inner hole of an end sleeve 23 and then through the middle hole of a planetary gear 24, and is fixedly connected to the planetary gear 24 in a detachable manner.

[0039] The pitch circle of planetary gear 24 is equal to the thread pitch diameter of roller 2;

[0040] Each of the cages 4 has a toothed ring 13 on its outer side, which meshes with the corresponding planetary gear 24;

[0041] The left side of the lead screw 3 has an extension rod section 33, which extends to the left from the left end hole 51 of the main housing 5.

[0042] When the device is running, the nut 1 rotates under the drive of the power mechanism and drives the extension segment 33 of the lead screw to move axially through the roller 2.

[0043] Preferably,

[0044] The roller has a smooth annular groove 25 in the middle of its external thread 21; the diameter of the annular groove 25 is smaller than the minor diameter of the external thread 21 of the roller.

[0045] Includes a circular subframe 42;

[0046] During assembly, the annular groove 25 of each roller is inserted into a retaining hole 421 of a sub-frame;

[0047] The diameter of the retaining hole 421 of the subframe is the same as the outer diameter of the roller's middle annular groove 25;

[0048] The retaining hole 421 of the subframe has an inwardly facing subframe notch 4211;

[0049] The width of the subframe notch 4211 is not less than the diameter of the annular groove 25.

[0050] Preferably,

[0051] The device includes a nut outer base cylinder 100,

[0052] The nut 1 is fixed inside the outer base cylinder 100.

[0053] The power mechanism drives the lead screw 3 to rotate via a torque transmission component;

[0054] The thread direction of the roller 2 is the same as that of the nut 1 and the lead screw 3;

[0055] One end of the lead screw 3 is the power output end;

[0056] The total length of the external thread 21 of the lead screw is less than the total length of the external thread 21 of the roller, and the difference is approximately equal to the working stroke of the device.

[0057] Compared to existing technologies, the planetary roller screw drive device proposed in this invention has a significantly reduced length-to-diameter ratio for the nut 1, even approaching 1, which significantly reduces the difficulty of machining and grinding the internal thread 11 of the nut. Furthermore, this invention avoids interference between the planetary gears 24 at both ends of the roller 2 and the internal thread 11 of the nut and the external thread 31 of the screw. It eliminates the need for combined machining of the tooth profile and thread at both ends of the roller 2, and the gears and rollers can be machined separately and assembled later. This fully utilizes the mature precision machining technology and existing equipment for screws and pinions, providing highly favorable conditions for further reducing product costs.

[0058] In this document, the terms "left" and "right" are used with reference to the top, bottom, left, and right of the referenced figures. These two directional terms are only for the purpose of accurately describing the relative positional relationship of the various parts of the present invention, and are not intended to indicate or imply that the components referred to must have a specific orientation, or must be combined and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0059] More specific technical features and beneficial effects of the present invention will be described in further detail in the following embodiments with reference to the accompanying drawings. Attached Figure Description

[0060] Figure 1 This is a three-dimensional schematic diagram of the cross-sectional structure of the assembly and its positional relationship with the main components in Example 1;

[0061] Figure 2 These are schematic cross-sectional views and enlarged views of the structure after removing the roller assembly in Example 1;

[0062] Figure 3 This is a perspective view of the assembly state of the cage and a roller in Embodiment 1;

[0063] Figure 4 This is a three-dimensional schematic diagram of the assembly relationship at one end of the roller assembly in Example 1;

[0064] Figure 5 These are perspective views of the roller assembly, lead screw, and nut assembly, and a separate perspective view of the lead screw, as described in Example 1.

[0065] Figure 6 This is a three-dimensional cross-sectional view of the assembly of the roller group, lead screw, motor rotor base tube, and motor rotor magnet group in Example 1.

[0066] Figure 7 This is a three-dimensional cross-sectional view of the complete assembly of Example 1;

[0067] Figure 8 This is a three-dimensional schematic diagram of the cross-sectional structure of the assembly and its positional relationship with the main components in Embodiment 2;

[0068] Figure 9 This is a three-dimensional sectional view of the assembly of the nut, nut outer base cylinder, cage, gear ring and subframe in Embodiment 2;

[0069] Figure 10 Is Figure 9 A three-dimensional sectional view of the assembly relationship of the component shown, which is fitted with a roller, an end sleeve, and a planetary gear.

[0070] Figure 11 This is a three-dimensional schematic diagram of the assembly relationship of one end of the roller assembly in Example 2;

[0071] Figure 12 This is a three-dimensional schematic diagram of the assembly components of the roller assembly and the lead screw in Example 2;

[0072] Figure 13 This is a three-dimensional sectional view of the assembly of the roller group, lead screw, nut, and nut outer base cylinder in Example 2;

[0073] Figure 14 yes Figure 11 A three-dimensional sectional view of the assembly shown after the motor rotor magnet assembly and bearings have been added.

[0074] Figure 15 yes Figure 14 A three-dimensional sectional view from another perspective;

[0075] Figure 16 This is a three-dimensional cross-sectional view of the assembly structure in Example 2;

[0076] Figure 17 This is a three-dimensional schematic diagram of the cross-sectional structure of the assembly and its positional relationship with the main components in Example 3;

[0077] Figure 18 These are three-dimensional sectional views and partial enlarged views of the assembly of the roller group, lead screw, nut, nut outer base cylinder, and motor rotor magnet group in Example 3.

[0078] Figure label:

[0079] 1_Nut, 100_Nut outer base tube, 11_Nut internal thread, 12_Nut extension tube, 121_Left end of nut extension tube

[0080] 1211_Left end screw hole of nut extension tube, 122_Cavity of nut extension tube, 13_Gear ring, 131_Gear ring fixing hole,

[0081] 14_Nut extension tube external spline type, 15_Nut spacer ring, 16_Nut locating pin hole;

[0082] 2_rollers, 200_roller group, 2001 roller group left rotation limit ring, 2002_roller group right rotation limit ring,

[0083] 21_External thread of roller, 22_Cylindrical end neck, 221_End neck flat face, 23_End sleeve, 24_Planetary gear,

[0084] 25_Roller middle ring groove, 26_Roller left limit ring, 27_Roller right bearing support ring;

[0085] 3_Lead screw, 31_External thread of the lead screw, 311_Transition section of the external thread of the lead screw, 32_Sun gear, 33_Extension rod section

[0086] 331 - Extension rod section flat surface; 34 - Lead screw tail pin; 35 - Lead screw left end; 36 - Lead screw spline hole.

[0087] 37_Screw power output end, 381_Screw end tube, 3811_Screw end tube sealing ring, 382_Screw end connecting shaft;

[0088] 4_Cage, 41_Cage hole, 411_Outward notch, 412_Inward notch, 42_Subframe, 421_Cage hole of subframe

[0089] 4211_Subframe notch, 43_Cage center hole,

[0090] 5_Outer shell, 51_Inner spline type of outer shell, 52_Left port of outer shell, 521_Flat surface of left port of outer shell, 53_Locking pin hole of outer shell,

[0091] 54_Left end cap of the outer casing;

[0092] 61_Motor stator coil assembly, 611_Motor stator coil assembly secondary housing, 62_Motor rotor magnet assembly,

[0093] 621_Motor rotor base tube, 622_Rotor bearing mounting ring;

[0094] 7_Bearing, 8_Spline rod, 9_Embodiment assembly. Detailed Implementation

[0095] Example 1 Figures 1 to 7 As shown, this is a planetary roller screw transmission device designed according to the basic principles of the present invention.

[0096] Figure 1 The central figure is assembly 9-1, an embodiment of this planetary roller screw drive. The main components in the figure are sectional views along the axis.

[0097] Its components include a main housing 5, inside which is installed a nut 1, six rollers 2 passing through the nut 1, and a lead screw 3 surrounded by the rollers 2; the external threads 21 of the rollers 2 engage with the external threads 31 of the lead screw 3, and engage with the internal threads 11 of the nut 1; a ring-shaped retainer 4 is inserted into each end of the rollers 2.

[0098] The left end of nut 1 is fixedly connected to the right end of a nut extension tube 12 by means of a fitting and pin fixing method.

[0099] The inner diameter of the cavity of the nut extension tube 12 is larger than the major diameter of the internal thread 11 of the nut.

[0100] The outer spline type 14 of the nut extension tube 12, which is set on the outer cylindrical surface of the nut extension tube 12, matches the inner spline type 51 of the outer shell, so that the nut extension tube 12 is circumferentially fixed relative to the main outer shell 5.

[0101] The left end 121 of the nut extension tube extends to the left from the left end hole 52 of the housing. The screw hole 1211 at the left end of the nut extension tube can be used to install working modules, such as push rods or pull rods with end holes, as needed.

[0102] See Figure 2The right end of the lead screw 3 is inserted into the motor rotor base tube 621 and fixedly connected to it by the lead screw tail pin 34. The cylindrical surface of the motor rotor base tube 621 is circumferentially distributed with strip magnets, forming the motor rotor magnet group 62.

[0103] The lead screw 3 and the motor rotor base tube 621 are mounted inside the rear end of the inner cavity of the main housing 5 via a roller assembly right-hand rotation limit ring 2002, a rotor bearing mounting ring 622, and a pair of angular contact bearings 7. In this way, the lead screw 3 is axially fixed relative to the main housing 5 and can only rotate circumferentially.

[0104] The right side of the main housing 5 contains a motor stator coil group 61. For the sake of simplicity, the motor stator coil group 61 in the accompanying drawings of each embodiment in this article adopts a schematic ring structure. The right end of the main housing 5 is fitted and connected to the motor stator coil group sub-housing 611.

[0105] This embodiment is equivalent to the known reverse planetary ball screw principle, so the thread direction of its roller 2 is opposite to that of the nut 1 and the screw 3.

[0106] See Figure 3 , Figure 4 Each roller 2 has cylindrical end necks 22 at both ends, and each cylindrical end neck 22 is inserted into the inner hole of a circular end sleeve 23. The end sleeve 23 can be inserted into a retaining hole 41 of the same diameter in the retainer 4. The retaining hole 41 has an outward notch 411, the width of which is smaller than the outer diameter of the end sleeve 23 and larger than the inner diameter of the end sleeve 23.

[0107] When assembling the roller assembly 200, which includes the lead screw 3, rollers 2, cage 4, end sleeve 23, and planetary gears 24, the cage 4 should first be fitted onto both ends of the external thread 31 of the lead screw. Then, the cylindrical end neck 22 of each roller 2 should be inserted into the outward notch 411 of the cage 4 in sequence, and the external thread 21 of the roller should be aligned with the external thread 31 of the lead screw and engaged with each other. After that, the end sleeve 23 should be fitted onto the cylindrical end neck 22 and inserted into the retaining hole 41 of the cage 4, so that each roller 2 is maintained in a planetary circumferential distribution position with the lead screw 3.

[0108] Next, the sun gear 32 with the central hole is fitted into and fixedly installed on the outside of the left and right retainers 4 of the lead screw 3, abutting against the retainers 4. The positioning and fixing connection between the sun gear 32 and the lead screw 3 can be accomplished using a prefabricated keyway structure. The outside of the sun gear 32 can be positioned using a retaining ring.

[0109] At this point, a set of planetary gears can be installed on the right end cylindrical neck 22 of the roller assembly 200. The cylindrical neck 22 has a flat surface 221, and the central bore of the planetary gear 24 also has a matching flat surface. The central bore diameter of the planetary gear 24 is equal to that of the cylindrical neck 22 of the roller 2, and they are interference fit. Of course, a clearance fit can also be used and a retaining ring can be provided. The installed right-end planetary gear 24 meshes with the right-end sun gear 32.

[0110] See Figure 5 Since the planetary gear 24 has not yet been installed on the left end of the roller assembly 200, the nut 1 can be gradually screwed into the roller assembly 200 from the left end and fit within the external thread 21 of the rollers of the roller assembly 200.

[0111] After inserting nut 1, another set of planetary gears 24-2 is installed on the left end of roller assembly 200 in the manner described above. The reason why this set of planetary gears 24-2 is not pre-installed is that the tip circle of planetary gear 24 will prevent the internal thread 11 of nut from being fitted into roller assembly 200.

[0112] Each sun gear 32 of the lead screw 3 meshes with its corresponding planetary gear 24. The right sun gear 32-2 can be machined separately and assembled with the lead screw 3 by means of a keyway or other fixed connection, or it can be machined as an integral part of the lead screw 3.

[0113] See Figure 5 The external thread 31 of the lead screw can be machined continuously or segmented as shown in the figure, with a transition section 311 reserved between each segment of the external thread 31. This is to reduce excessive contact between the roller 2 and the external thread 31 of the lead screw, and to reduce the amount of fine machining work required for the external thread 31 of the lead screw.

[0114] See Figure 6 ,exist Figure 5 Based on the assembly, a right roller bearing support ring 27 and a pair of angular contact bearings 7 are further installed on the right extension section 33 of the lead screw 3. The lead screw tail pin 34 fixes the motor rotor base tube 621 to the right extension section 33 of the lead screw. A motor rotor magnet assembly 62 is installed around the outside of the motor rotor base tube 621. A left roller limiting ring 26 is installed at the left end 35 of the lead screw.

[0115] See Figure 7 ,exist Figure 6 Based on this, the right end of the nut extension tube 12 is fixedly connected to the left end of the nut 1. Then, the main housing 5 and the motor stator coil group auxiliary housing 611 are installed.

[0116] After the motor is started, the motor rotor base tube 621 drives the lead screw 3 to rotate within the roller assembly 200, and drives the nut extension tube 12 to extend and retract. The screw hole 1211 at the left end of the nut extension tube 121 can be used to install working ends of different functions to complete the push and pull operation of the work object.

[0117] In this embodiment, the length of the internal thread 11 of the nut is 3 cm, and the length of the external thread 21 of the roller is 12 cm, with a difference of approximately 9 cm. That is, the working stroke is 9 cm. Of course, in order to improve the rated load capacity, the length of the internal thread 11 of the nut can be appropriately extended according to specific calculations.

[0118] Compared to existing reverse planetary roller screw products, the length of the internal thread 11 of the nut in this embodiment is significantly shortened, greatly reducing its machining difficulty. Although the length of the roller 2 is longer than that of existing products, its two ends do not need to be machined together to form the tooth profile of the planetary gear 24; only a simple pre-made cylindrical end neck 22 with a flat surface is required. The planetary gear 24 and the sun gear 32 can be mass-produced using existing, very mature, reliable, and efficient machining equipment and processes, and then efficiently assembled in the later stages through simple procedures. Given the existing conditions, this embodiment makes it easier to realize an automated assembly line for the product, thus creating favorable conditions for high-quality, low-cost production.

[0119] Example 2 Figures 8 to 16 As shown. This is a special application of the present invention based on standard planetary roller screw technology.

[0120] The main components of this embodiment include an integral main housing 5, with a flat surface 521 on the left port 52 of the housing, and a motor stator coil group 61 installed on the right side of the inner cavity of the housing.

[0121] This embodiment has two nuts 1, a set of rollers 200, and a lead screw 3.

[0122] Each roller 2 has a cylindrical end neck 22 with a flat end neck 221 at both ends. The external thread 21 of each roller has a smooth annular groove 25 in the middle; the diameter of the annular groove 25 is smaller than the minor diameter of the external thread 21 of the roller.

[0123] See Figure 9 , Figure 10 Two nuts 1 are installed in the inner cavity of the same nut outer base cylinder 100 by means of nut positioning pin holes 16.

[0124] There is a retainer 4 and a gear ring 13 at each end of the inner cavity of the outer base cylinder 100 of the nut. There is also a secondary retainer 42 between the left and right nuts 1. See also Figure 11 , Figure 12The retaining hole 421 of the sub-frame has an inwardly facing sub-frame notch 4211. The width of the sub-frame notch 4211 is not less than the diameter of the annular groove 25. The diameter of the retaining hole 421 of the sub-frame is the same as the outer diameter of the annular groove 25 in the roller.

[0125] The gear ring 13 is fixedly connected to the outer base cylinder 100 of the nut by a locating pin.

[0126] See Figure 10 , Figure 11 , Figure 12 .exist Figure 9 Based on the assembly, the cylindrical end neck 22 of each roller 2 is inserted into the inward notch 412 of the cage 4 in sequence, the annular groove 25 of the roller is inserted into the retaining hole 421 of the sub-frame, and the external thread 21 of the roller is aligned with the internal thread 11 of the nut and meshes with each other. Then, the end sleeve 23 is put on the cylindrical end neck 22 and inserted into the retaining hole 41 of the cage 4, so that each roller 2 is maintained in the planetary circumferential distribution position with the nut 3.

[0127] See Figure 14 , Figure 15 After assembling all rollers 2, insert the lead screw 3 into the center hole of the cage 4 and gradually screw it into the center of the roller assembly 200, so that the external thread 31 of the lead screw meshes with the external threads 21 of each roller. Then, press... Figure 14 As shown, install planetary gear 24, left rotation limit ring 2001 of roller assembly, right rotation limit ring 2002 of roller assembly, bearing 7, motor rotor magnet assembly 62, and motor rotor base tube 621 to complete the pre-installation of the rotation module of the device.

[0128] See Figure 16 The assembled rotary module described above is inserted into the main housing 5 and sealed with the left port 52 of the housing.

[0129] See Figure 1 The extension rod section flat surface 331 matches the flat surface 521 of the left end of the housing, so that the lead screw 3 remains circumferentially fixed relative to the main housing 5.

[0130] After the motor is started, the motor rotor base tube 621 drives the outer base cylinder 100 of the nut and the nut 1 to rotate, and drives the extension rod section 33 of the lead screw 3 to move axially, so as to push and pull the working object with the left end 35 of the lead screw.

[0131] In this embodiment, the length of the external thread 31 of the lead screw is 3cm, and the length of the external thread 21 of the roller is 12cm. The difference is 9cm of working stroke.

[0132] Compared to Example 1, the advantage of this example is that the extension segment 33 of the rod-shaped lead screw 3 with a diameter of only 1.2 cm serves as the telescopic working part, which has better spatial adaptability than the thick tubular nut extension tube 12 with a diameter of several centimeters used in Example 1. For example, when used in the leg joints of a highly realistic humanoid robot, the working end is more conducive to covering the relatively slender simulated skin shape.

[0133] Example 3 Figure 17 , Figure 18 As shown. This is another special application of the present invention based on standard planetary roller screw technology.

[0134] The main components of this embodiment include the main outer casing 5.

[0135] See Figure 17 , Figure 18 This embodiment uses the same structure as Embodiment 2, including the two nuts 1, rollers 2 and roller assembly 200, as well as the same cage 4, sub-frame 42, gear ring 13 and planetary gear 24.

[0136] Two nuts 1 are installed inside the main housing 5 using the nut locating pin holes 16.

[0137] Inside the main outer shell 5, according to a similar... Figure 9 As shown, two retainers 4 and two toothed rings 13 are installed. A sub-retainer 42 is installed between the left and right nuts 1. Then, according to Embodiment 1... Figure 11 As shown, the cylindrical end neck 22 of each roller 2 is inserted into the inward notch 412 of the cage 4 in sequence inside the main housing 5. The annular groove 25 of the roller is inserted into the retaining hole 421 of the sub-frame. The external thread 21 of the roller is aligned with the internal thread 11 of the nut and they mesh with each other. Then, the end sleeve 23 is put on the cylindrical end neck 22 and inserted into the retaining hole 41 of the cage 4, so that each roller 2 is maintained in a planetary circumferential distribution position with the nut 3.

[0138] Insert the lead screw 3 into the center hole of the cage 4 and gradually screw it into the center of the roller assembly 200 so that the external thread 31 of the lead screw meshes with the external thread 21 of each roller.

[0139] according to Figure 17 As shown, planetary gear 24, bearing 7, motor rotor base tube 621, and motor rotor magnet assembly 62 are installed; then the motor stator coil assembly housing 611 containing the motor stator coil assembly 61 is fixedly connected to the right end of the main housing 5.

[0140] The structure of the lead screw power output terminal 37 at the left end of the extension segment 33 of the lead screw 3 is as follows: Figure 18As shown, two angular contact bearings 7 installed in the lead screw end sleeve 381 form a mutually axially fixed and rotatable working end at the left end of the extension section 33 of the lead screw 3 via the lead screw end connecting shaft 382 and the lead screw end sleeve sealing ring 3811.

[0141] The lead screw 3 is a hollow tube with a hexagonal lead screw spline hole 36 inside. The spline rod 8, which is axially fixedly connected to the motor rotor base tube 621 with the same spline hole, is inserted into the lead screw spline hole 36 and can slide relative to it axially.

[0142] After the motor is started, the motor rotor base tube 621 drives the spline rod 8 and the lead screw 3 to rotate, driving the extension rod segment 33 to rotate and extend, so that the lead screw power output end 37 at the left end of the lead screw 3 pushes and pulls the work object to do work.

[0143] Similar to Example 2, the working stroke in this example is also 9cm.

[0144] Compared to Embodiment 2, in this embodiment, the extension segment 33 of the lead screw 3 performs both rotation and extension / retraction movements simultaneously during operation. Therefore, it is generally necessary to configure... Figure 18 The special non-rotating working end shown.

[0145] It should be noted that, for ease of observation, some components shown in the attached figures are presented in a sectional view, and individual rollers in the roller assembly are also cut out or hidden. The irregularly shaped main housing 5 can be constructed using a half-molded structure, assembled with fasteners. In practical applications, the number of rollers in the roller assembly is obviously not limited to the six shown in the attached figures. The internal thread of the nut is generally a multi-start thread.

Claims

1. A planetary roller screw transmission device, comprising a nut (1), multiple rollers (2) inserted into the nut (1), and a screw (3) surrounded by the rollers (2); the external thread (21) of the rollers (2) meshes with the external thread (31) of the screw (3) and meshes with the internal thread (11) of the nut (1); a ring-shaped retainer (4) is inserted into each end of the rollers (2); Its characteristics are: The total length of the external thread (31) of the lead screw (3) is not greater than the total length of the external thread (21) of the roller (2); The total length of the external thread (21) of the roller (2) is not less than the total length of the internal thread (11) of the nut (1); The total length of the external thread (31) of the lead screw (3) is not equal to the total length of the internal thread (11) of the nut (1); The difference between the total length of the external thread (31) of the lead screw (3) and the total length of the internal thread (11) of the nut (1) is approximately equal to the working stroke of the device; When the device is running, the lead screw (3) and the nut (1) rotate relative to each other under the drive of the power mechanism; When the device is running, the external thread (31) of the lead screw (3) and the internal thread (11) of the nut (1) are always located between the cages (4) at both ends of the roller (2).

2. The planetary roller screw transmission device according to claim 1, characterized in that: The device includes a main housing (5). The left end of the nut (1) is fixedly connected to the right end of a nut extension tube (12); The inner diameter of the cavity of the nut extension tube (12) is larger than the major diameter of the nut's internal thread (11); The nut (1) and the nut extension tube (12) are circumferentially fixed relative to the main housing (5); The thread direction of the roller (2) is opposite to that of the thread direction of the nut (1) and the lead screw (3); The lead screw (3) is axially fixed relative to the main housing (5); The left end (121) of the nut extension tube extends to the left from the left end hole (51) of the housing; The total length of the internal thread (11) of the nut is less than the total length of the external thread (21) of the roller, and the difference is approximately equal to the working stroke of the device.

3. The planetary roller screw transmission device according to claim 2, characterized in that: Each of the rollers (2) has cylindrical end necks (22) at both ends. Each cylindrical end neck (22) is inserted into the inner hole of a circular end sleeve (23). The end sleeve (23) can be inserted into the retaining hole (41) of the same diameter of the retainer (4). The retaining hole (41) has an outward notch (411), the width of which is smaller than the outer diameter of the end sleeve (23) and larger than the inner diameter of the end sleeve (23); The cylindrical end neck (22) of each roller (2) passes through the inner hole of an end sleeve (23) and then through the middle hole of a planetary gear (24), and is fixedly connected to the planetary gear (24) in a detachable manner. The pitch circle of the planetary gear (24) is equal to the thread pitch diameter of the roller (2); The external thread (31) of the lead screw has sun gears (32) at both ends, and each sun gear (32) meshes with the corresponding planetary gears (24); When the device is running, the lead screw (3) rotates under the drive of the power mechanism and drives the nut extension tube (12) to move axially through the roller (2).

4. The planetary roller screw transmission device according to claim 1, characterized in that: The device includes a main housing (5). The nut (1) is axially fixed relative to the main housing (5); The lead screw (3) is circumferentially fixed relative to the main housing (5); The thread direction of the roller (2) is the same as that of the nut (1) and the lead screw (3); The total length of the external thread (21) of the lead screw is less than the total length of the external thread (21) of the roller, and the difference is approximately equal to the working stroke of the device.

5. A planetary roller screw transmission device according to claim 4, characterized in that: Each of the rollers (2) has cylindrical end necks (22) at both ends. Each cylindrical end neck (22) is inserted into the inner hole of a circular end sleeve (23). The end sleeve (23) can be inserted into the retaining hole (41) of the same diameter of the retainer (4). The retaining hole (41) has an inward notch (412), the width of which is smaller than the outer diameter of the end sleeve (23) and larger than the inner diameter of the end sleeve (23); The cylindrical end neck (22) of each roller (2) passes through the inner hole of an end sleeve (23) and then through the middle hole of a planetary gear (24), and is fixedly connected to the planetary gear (24) in a detachable manner. The pitch circle of the planetary gear (24) is equal to the thread pitch diameter of the roller (2); Each of the cages (4) has a toothed ring (13) on its outer side, which meshes with the corresponding planetary gears (24); The lead screw (3) has an extension rod section (33) on the left side, which extends to the left from the left end hole (51) of the main housing (5); When the device is running, the nut (1) rotates under the drive of the power mechanism and drives the extension segment (33) of the lead screw to move axially through the roller (2).

6. A planetary roller screw transmission device according to claim 5, characterized in that: The roller has a smooth annular groove (25) in the middle of its external thread (21); the diameter of the annular groove (25) is smaller than the minor diameter of the external thread (21) of the roller. Includes a circular attachment (42); During assembly, each roller's annular groove (25) is inserted into a retaining hole (421) of an auxiliary frame. The diameter of the retaining hole (421) of the attachment is the same as the outer diameter of the inner ring groove (25) of the roller; The retaining hole (421) of the attachment has an inward attachment notch (4211). The width of the bracket notch (4211) is not less than the diameter of the annular groove (25).

7. A planetary roller screw transmission device according to claim 1, characterized in that: The device includes a nut outer base sleeve (100). The nut (1) is fixed inside the outer base cylinder (100). The power mechanism drives the lead screw (3) to rotate via a torque transmission component; The thread direction of the roller (2) is the same as that of the nut (1) and the lead screw (3); One end of the lead screw (3) is the power output end; The total length of the external thread (21) of the lead screw is less than the total length of the external thread (21) of the roller, and the difference is approximately equal to the working stroke of the device.

8. A planetary roller screw transmission device according to claim 7, characterized in that: The roller has a smooth annular groove (25) in the middle of its external thread (21); the diameter of the annular groove (25) is smaller than the minor diameter of the external thread (21) of the roller. Includes a circular attachment (42); During assembly, each roller's annular groove (25) is inserted into a retaining hole (421) of an auxiliary frame. The diameter of the retaining hole (421) of the attachment is the same as the outer diameter of the inner ring groove (25) of the roller; The retaining hole (421) of the attachment has an inward attachment notch (4211). The width of the bracket notch (4211) is not less than the diameter of the annular groove (25).

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