Fast planetary roller screw drive

Abstract

In order to solve the problems that the telescopic speed of a reverse planetary roller lead screw is not easy to increase, and a nut and a roller with a large length-diameter ratio are difficult to machine, the invention provides a rapid planetary roller lead screw transmission device. The device is characterized in that the lead screw, the nut and the roller in the same device all comprise left-hand threads and right-hand threads. Through multiple combination modes of the lead screws, the nuts and the rollers with different rotating directions, the working speed of the device can be increased by several times without increasing the rotating speed of the motor and without increasing the lead. Further, the thread length of the roller can be larger than the thread length of the nut and the thread length of the lead screw. The screw thread length of the nut can be less than 3cm, the length-diameter ratio of the nut can be less than 2, two ends of the pin roller can adopt externally mounted planetary gears with complete tooth types, and the pin roller and the planetary gears do not need to be integrally processed together, so that the processing difficulty is obviously reduced.

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 some applications, especially as actuators for the limbs of humanoid robots, high extension and retraction speeds are required. Currently, the only ways to increase these speeds are to increase the motor speed or the lead. However, to ensure the actuator's load capacity, self-locking capability, heat dissipation, and operational accuracy, the increase in motor speed and lead is clearly limited.

[0004] 2. 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.

[0005] 3. Due to limitations in existing technology, the length of the roller thread must be much shorter than the thread length of the nut. However, in principle, 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 both gears and threads at both ends of the roller, creating a combined gear and thread section. While this structure ensures no interference between the planetary gear and the thread, guaranteeing normal transmission of the planetary roller leadscrew, this composite 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 and gear section are more prone to wear, affecting the limiting and guiding function of the roller. Summary of the Invention

[0006] To address the aforementioned deficiencies in the prior art, this invention proposes a rapid planetary roller screw transmission device, comprising a nut housed within a main housing, multiple rollers inserted into the nut, and a screw surrounded by the rollers; the external threads of the rollers engage with the external threads of the screw and with the internal threads of the nut; retainers are inserted into both ends of the rollers; during operation, the screw and nut rotate relative to each other under the drive of a power mechanism.

[0007] Its unique feature is that its composition includes a lead screw with a left-hand external thread, a lead screw with a right-hand external thread, a nut with a left-hand internal thread, a nut with a right-hand internal thread, a roller with a left-hand external thread, and a roller with a right-hand external thread.

[0008] A lead screw with a left-hand external thread is circumferentially fixed relative to a lead screw with a right-hand external thread;

[0009] A nut with a left-hand internal thread is circumferentially fixed relative to a nut with a right-hand internal thread.

[0010] Based on the aforementioned necessary technical features, preferably,

[0011] The nuts include a left-handed nut and a right-handed nut; these two nuts are circumferentially fixed relative to the housing; one nut is axially movable along the housing and one end of it is connected to a working push rod; the other nut is fixedly connected to the housing.

[0012] A nut with a left-hand internal thread contains a set of rollers with a left-hand external thread.

[0013] A nut with a right-hand internal thread contains a set of rollers with a right-hand external thread.

[0014] The lead screw has a spline hole as its axis. The lead screw has a left-hand external thread and a right-hand external thread. The left-hand external thread of the lead screw is screwed into the roller assembly inside the nut with the left-hand internal thread, and the right-hand external thread of the lead screw is screwed into the roller assembly inside the nut with the right-hand internal thread.

[0015] There is an axially fixed spline rod that passes through the spline hole of the aforementioned lead screw;

[0016] The power mechanism drives the spline rod to rotate, and the spline rod in turn drives the lead screw to rotate.

[0017] Preferably,

[0018] The nuts include a left-handed nut and a right-handed nut; these two nuts are circumferentially fixed relative to the housing and are axially movable along the inner cavity of the housing.

[0019] A nut with a left-hand internal thread contains a set of rollers with a right-hand external thread.

[0020] A nut with a right-hand internal thread contains a set of rollers with a left-hand external thread.

[0021] There are two axially fixed lead screws, one of which has a left-hand thread and the other has a right-hand thread.

[0022] The external thread of a lead screw with a left-hand thread is screwed into the roller assembly inside a nut with a right-hand thread, and the external thread of a lead screw with a right-hand thread is screwed into the roller assembly inside a nut with a left-hand thread.

[0023] The two lead screws are driven and rotated by the power mechanism located in the middle of the housing.

[0024] Preferably,

[0025] It includes three nuts distributed on the left, center and right, which are fixed circumferentially relative to the outer shell;

[0026] The nut in the middle is fixedly connected to the nut on the right and can move along the axial direction of the outer casing;

[0027] The nut on the left is fixedly connected to the left side of the outer casing;

[0028] The internal thread of the middle nut has the opposite direction of rotation to the internal threads of the other two nuts;

[0029] Each of the three nuts contains a set of rollers, and the internal thread of each nut is in the same direction as the external thread of the roller inside the nut.

[0030] Includes two lead screws, one on the left and one on the right, both of which have spline holes;

[0031] The lead screw on the left has two sections of external threads with opposite directions of rotation. The direction of rotation of the left section of external thread is the same as that of the internal thread of the left nut; the direction of rotation of the right section of external thread is the same as that of the internal thread of the nut in the middle.

[0032] The left-hand section of the lead screw's external thread is screwed into the roller assembly inside the left-hand nut, and the right-hand section of the lead screw's external thread is screwed into the roller assembly inside the middle nut.

[0033] The right-hand lead screw has an external thread on its left side, which screws into the roller assembly inside the right-hand nut.

[0034] The direction of the external thread on the left side of the right-hand lead screw is the same as the direction of the internal thread on the right-hand nut.

[0035] The right end of the lead screw on the right extends from the hole on the right end of the housing;

[0036] There is a splined rod whose left end is fixedly connected to the outer casing, and the splined rod passes through the spline hole of the aforementioned lead screw;

[0037] The power mechanism drives each nut to rotate and causes the two lead screws to move axially.

[0038] Preferably,

[0039] It includes two nuts, one on the left and one on the right, which are fixedly connected to each other and axially fixed relative to the outer casing;

[0040] The internal thread of the nut on the left has the opposite direction of rotation to that of the nut on the right.

[0041] The rollers with left-hand external threads and the rollers with right-hand external threads are located in different nuts;

[0042] The internal thread of each nut is in the same direction as the internal thread of the roller located therein;

[0043] It includes two lead screws, one on the left and one on the right; these two lead screws are fixed circumferentially relative to the housing and can move axially along the housing.

[0044] The right side of the lead screw on the left has an external thread, and the left side of the lead screw on the right has an external thread.

[0045] The external threads of the left and right lead screws rotate in opposite directions;

[0046] The external thread of the lead screw on the left is screwed into the roller assembly inside the nut on the left.

[0047] The external thread of the right-hand lead screw is screwed into the roller assembly inside the right-hand nut;

[0048] The power mechanism drives each nut to rotate and causes the two lead screws to move in opposite directions along the axial direction.

[0049] Preferably,

[0050] Includes a second power mechanism that can drive the lead screw to rotate;

[0051] The second power mechanism can operate independently.

[0052] Preferably,

[0053] It includes two nuts, one on the left and one on the right, which are fixedly connected to each other;

[0054] The internal thread of the nut on the left has the opposite direction of rotation to that of the nut on the right.

[0055] The rollers with left-hand external threads and the rollers with right-hand external threads are respectively inserted into different nuts;

[0056] The internal thread of the nut on the left has the same direction of rotation as the external thread of the roller inside it;

[0057] The internal thread of the nut on the right has the same direction of rotation as the external thread of the roller inside it;

[0058] It includes two lead screws, one on the left and one on the right, which are fixed circumferentially relative to the outer casing; wherein, the lead screw on the left can move axially along the outer casing, and the right end of the lead screw on the right is fixedly connected to the right end of the outer casing.

[0059] The right side of the lead screw on the left has an external thread, and the left side of the lead screw on the right has an external thread.

[0060] The external threads of the left and right lead screws rotate in opposite directions;

[0061] The external thread of the lead screw on the left is screwed into the roller assembly inside the nut on the left.

[0062] The external thread of the right-hand lead screw is screwed into the roller assembly inside the right-hand nut;

[0063] The power mechanism drives each nut to rotate.

[0064] By employing the aforementioned technique of multiplying the speed of the end component by using threads of different helical directions, the extension and retraction speed of the working component, which serves as the final power output end of the device, will be at least double that of the component driven by the initial driving force of the power mechanism, and may even reach 3, 4, 5, or 6 times. Furthermore, this increase in the speed of the working end does not require an increase in the rotational speed of the initial power input mechanism, nor does it require an increase in the thread pitch or the lead of the lead screw and nut. With appropriate lead design, self-locking capability can even be maintained while increasing the extension and retraction speed of the device.

[0065] In the same device, using two motors to drive the lead screw and nut respectively will not only further increase the extension and retraction speed of the working parts, but also allow the extension and retraction state of the power output end to be smoothly switched between extension, stop and retraction simply by changing the speed of the two motors without changing their respective rotation direction.

[0066] Preferably,

[0067] The total length of the external threads of each lead screw shall not be greater than the total length of the external threads of the roller around which the lead screw is surrounded;

[0068] The total length of the external threads of each roller is not less than the total length of the internal threads of the nut around which the roller is surrounded;

[0069] The total length of the external threads of each lead screw is not equal to the total length of the internal threads of the nut around which the lead screw is wrapped;

[0070] Each roller has a cylindrical neck at both ends inserted into the inner hole of a circular end sleeve, which can be inserted into a retaining hole of the same diameter as the cage.

[0071] The hole should have an outward notch, the width of which is less than the outer diameter of the end sleeve and greater than the inner diameter of the end sleeve.

[0072] The cylindrical end neck of each roller passes through the inner hole of an end sleeve, then through the middle hole of a planetary gear, and is fixedly connected to the planetary gear.

[0073] The pitch circle of a planetary gear is equal to the thread pitch diameter of a roller.

[0074] The lead screw has sun gears at both ends of its external thread, and each sun gear meshes with a corresponding planetary gear.

[0075] Preferably,

[0076] The total length of the external threads of each lead screw shall not be greater than the total length of the external threads of the roller around which the lead screw is surrounded;

[0077] The total length of the external threads of each roller is not less than the total length of the internal threads of the nut around which the roller is surrounded;

[0078] The total length of the external threads of each lead screw is not equal to the total length of the internal threads of the nut around which the lead screw is wrapped;

[0079] Each roller has a cylindrical neck at both ends inserted into the inner hole of a circular end sleeve, which can be inserted into a retaining hole of the same diameter as the cage.

[0080] The hole should have an inward notch, the width of which is smaller than the outer diameter of the end sleeve and larger than the inner diameter of the end sleeve.

[0081] The cylindrical end neck of each roller passes through the inner hole of an end sleeve, then through the middle hole of a planetary gear, and is fixedly connected to the planetary gear.

[0082] The pitch circle of a planetary gear is equal to the thread pitch diameter of a roller.

[0083] The outer side of the cage has toothed rings, each of which meshes with a corresponding planetary gear;

[0084] Each toothed ring is circumferentially fixed relative to the nut.

[0085] With the addition of the aforementioned preferred features, compared to the prior art, the length-to-diameter ratio of the nut 1 in the proposed rapid planetary roller screw transmission device is significantly reduced, even to near 1, significantly reducing the difficulty of machining and grinding the internal thread 11 of the nut. Furthermore, the present invention also 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, eliminating the need for combined machining of the tooth profile and thread at both ends of the roller 2. Moreover, the gears and rollers can be machined separately and assembled later, fully utilizing the mature precision machining technology and existing equipment for screws and pinions, providing highly favorable conditions for further reducing product costs.

[0086] In this document, the terms "left," "center," and "right" are used with reference to the left, center, and right of the referenced figures; the term "inner" refers to the direction toward the geometric center of the device, and the term "outer" is the opposite of the term "inner"; the term "front" refers to the direction in which the referenced component is approximately to the left in the figure in which it is located, and the term "rear" is the opposite of "front."

[0087] These directional terms are used to accurately describe the relative positional relationships 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.

[0088] 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

[0089] 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;

[0090] Figure 2 These are a three-dimensional sectional view and a partial enlarged view of the assembly structure of Example 1;

[0091] Figure 3 These are a three-dimensional structural diagram and a partial enlarged view of the disassembled moving parts inside the outer shell of Embodiment 1;

[0092] Figure 4 This is a three-dimensional schematic diagram of the assembly method of the cage, roller end, and end sleeve in Embodiment 1;

[0093] Figure 5 This is a three-dimensional schematic diagram of the assembly relationship of the nut, roller, cage, end sleeve, planetary gear, and gear ring in Example 1.

[0094] Figure 6 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;

[0095] Figure 7 This is a three-dimensional structural diagram of the disassembled moving parts inside the outer shell of Embodiment 2;

[0096] Figure 8 This is a three-dimensional schematic diagram of the assembly method of the cage, roller end, and end sleeve in Embodiment 2;

[0097] Figure 9 This is a three-dimensional schematic diagram of the assembly relationship of the lead screw, roller, cage, end sleeve, and sun gear in Example 2;

[0098] Figure 10 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;

[0099] Figure 11 These are a three-dimensional sectional view and a partial enlarged view of the assembly structure in Example 3;

[0100] Figure 12 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 4;

[0101] Figure 13 This is a three-dimensional cross-sectional view of the assembly of the outer shell and internal moving parts in Embodiment 4.

[0102] Figure 14 This is a three-dimensional schematic diagram of the cross-sectional structure of the assembly in Example 5 and its positional relationship with the main internal moving parts;

[0103] Figure 15 This is a three-dimensional schematic diagram of the cross-sectional structure of the assembly in Embodiment 5 and its positional relationship with the main internal shell components;

[0104] Figure 16 This is a three-dimensional schematic diagram and a partial enlarged view showing the positional relationship between the assembly of the movable parts and the main parts in Embodiment 5;

[0105] 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 6;

[0106] Figure 18 These are three-dimensional schematic diagrams and partial enlarged views of the assembly and some parts of the movable components in Embodiment 6;

[0107] Figure 19 This is a cross-sectional view of the assembly structure and a three-dimensional schematic diagram of several parts in Example 7;

[0108] Figure 20 This is a three-dimensional schematic diagram of the assembly of the moving parts and the outer base of the nut in Embodiment 7.

[0109] Figure label:

[0110] 1_Nut, 100_Nut outer base sleeve, 101_Nut outer base sleeve external spline, 102_Nut outer base sleeve internal spline,

[0111] 103_Nut outer base cylinder positioning pin hole, 11_Nut internal thread, 12_Nut extension tube, 121_Nut extension tube front end,

[0112] 1211_Nut extension tube front threaded hole, 122_Nut extension tube cavity, 123_Nut extension tube front connector.

[0113] 124_External spline of nut extension tube, 13_Gear ring, 131_Gear ring fixing hole, 14_External spline of nut,

[0114] 15_Nut spacer, 151_Intercalation groove, 16_Nut locating pin hole, 17_Nut front working push rod

[0115] 171_Nut front push rod seat, 172_Nut front push rod head, 181_Nut outer base cylinder front sealing ring,

[0116] 182_Nut outer base sleeve rear end sealing ring, 19_Double nut assembly, 2_Rollers, 200_Roller group,

[0117] 2001_Roller assembly rear bearing housing, 21_Roller external thread, 22_Cylindrical end neck, 221_End neck flat face, 23_End sleeve,

[0118] 24_Planetary gear, 25_Roller middle ring groove, 26_Roller front limit ring, 27_Roller rear bearing support ring,

[0119] 28_Roller retaining ring, 29_Wire retaining ring for bore, 3_Lead screw, 31_Lead screw external thread, 311_Lead screw external thread transition section

[0120] 32 - Sun gear, 33 - Lead screw extension segment, 331 - Lead screw extension segment flat surface, 332 - Lead screw extension segment spline.

[0121] 333_Lead screw extension section positioning hole.

[0122] 34 - Lead screw tail pin; 35 - Lead screw front head; 36 - Lead screw spline hole; 37 - Lead screw extension section front end.

[0123] 4_Cage, 41_Cage hole, 411_Outward notch, 412_Inward notch, 42_Subframe, 421_Cage hole of subframe

[0124] 4211_Subframe notch, 43_Cage center hole, 5_Main housing, 51_Housing internal spline type, 52_Housing front port,

[0125] 521_Flat front end of housing, 522_Front end cap of housing, 5221_Center hole of front end cap of housing

[0126] 5222_Flat face of the center hole of the front cover of the outer casing, 53_Rear port of the outer casing, 531_Flat face of the rear port of the outer casing, 532_Large cover of the rear port of the outer casing

[0127] 5321_Rear cover center hole of outer casing, 5322_Flat surface of the rear cover center hole of outer casing, 54_Locking pin hole of outer casing, 55_Secondary outer casing section,

[0128] 551 - Rear end hole of secondary housing section; 61 - Stator coil assembly of motor; 62 - Rotor magnet assembly of motor; 621 - Rotor base tube of motor.

[0129] 622_Rotor bearing mounting ring, 623_Motor rotor base tube spline hole, 7_Bearing, 8_Spline rod,

[0130] 81_Spline rod end pin, 9_Embodiment assembly of the embodiment. Detailed Implementation

[0131] Example 1 Figures 1 to 5 As shown. Example assembly 9-1 is as follows. Figure 1 As shown in the middle figure.

[0132] See Figure 1 , Figure 2 , Figure 3 This embodiment comprises a long tubular main housing 5, within which an internal spline 51 is provided. Two nuts 1-1 and 1-2 are installed inside the main housing 5. The outer cylindrical surface of the nuts has an external spline 14 that mates with the internal spline 51. The mating splines fix the nuts circumferentially relative to the main housing.

[0133] The two nuts 1-1 and 1-2 have opposite internal thread directions. Nut 1-1, with its left-hand internal thread, contains a set of rollers 200-1 with left-hand external threads; nut 1-2, with its right-hand internal thread, contains a set of rollers 200-2 with right-hand external threads. The external thread 21 of each roller is 7.5 cm long. The internal thread 11 of each nut is 6 cm long, slightly shorter than the external thread length of the rollers.

[0134] One of the two nuts 1-1 and 1-2, nut 1-1, is fixedly connected to the main housing 5 with a pin through the nut positioning pin hole 16 and the housing positioning pin hole 54, while the other nut 1-2 can move axially.

[0135] The outer end of the nut 1-2, which can move axially, is fixedly connected to the nut front push rod seat 171 of a nut front working push rod 17.

[0136] The front port 52 of the main housing 5 is fitted with a front port cover 522. The front working push rod 17 of the nut protrudes from the central hole 5221 of the front port cover of the main housing 5. The front push rod head 172 of the nut is the power output end of the device.

[0137] There is a 17cm long lead screw 3. One end of the lead screw 3 has a 3cm long left-hand external thread 31-1 and a 3cm long right-hand external thread 31-2. The axis of the lead screw 3 is a through spline hole 36. The diameter of the unthreaded middle section 38 of the lead screw is smaller than the minor diameter of the thread.

[0138] The left-hand external thread 31-1 of the lead screw 3 is screwed into the roller assembly inside the nut 1-1, whose internal thread is left-handed, and the right-hand external thread 31-2 of the lead screw 3 is screwed into the roller assembly inside the nut 1-2, whose internal thread is right-handed.

[0139] There is an axially fixed splined rod 8, which passes through the spline hole 36 of the lead screw 3. The shape of the splined rod 8 matches the spline hole 36 of the lead screw 3.

[0140] The outer end of the splined rod 8 passes through the rotor base tube 621 of the frameless motor, and the rotor magnet assembly 62 is installed around the rotor base tube 621. The rear port 53 of the main housing 5 is connected to the secondary housing section 55, and the stator coil assembly 61 of the frameless motor is installed inside the secondary housing section 55. The two ends of the rotor base tube 621 are mounted at the two ends of the stator coil assembly 61 of the main housing 5 by bearings 7.

[0141] Each roller 2 has a cylindrical end neck 22 with a diameter smaller than its thread minor diameter at both ends, and the cylindrical end neck 22 has an end neck flat surface 221.

[0142] The assembly method of the two roller assemblies 200-1 and 200-2 is as follows: Figure 2 , Figure 3 As shown. The cage 4n and the gear ring 13 are pre-installed at the two ports within the nut 1. The cage 4n has six retaining holes 41 evenly distributed around the central hole. Each retaining hole 41 has an inwardly facing notch 412. Each retaining hole 41 is fitted with an end sleeve 23. The outer diameter of the end sleeve 23 is the same as the diameter of the retaining hole 41, and the inner diameter of the end sleeve 23 is the same as the diameter of the cylindrical end neck 22 of the roller 2.

[0143] When installing rollers 2, each roller 2 must be inserted through the central hole of the cage 4, ensuring that the external thread 21 of the roller 2 engages with the internal thread 11 of the nut 1 in the correct phase. Then, move the cylindrical end necks 22 at both ends of the roller 2 through the inward notches 412 into the retaining holes 41. Next, place the end sleeve 23 over the cylindrical end necks 22 of the roller 2 and then insert it into the retaining holes 41 of the cage 4, preventing the roller 2 from dislodging from the retaining holes 41. The other rollers 2 are installed in the same manner.

[0144] Next, six planetary gears 24 are fitted onto one end of the cylindrical neck 22 of each roller 2 with an interference fit, and they mesh with the corresponding gear ring 13. The flat surface 221 of the cylindrical neck 22 matches the flat surface inside the planetary gear 24 to keep the roller 2 and the planetary gear 24 circumferentially fixed. The pitch circle of the planetary gear 24 is equal to the thread pitch diameter of the roller 2.

[0145] After installing the six planetary gears 24 at one end of the roller assembly 200, screw the external thread section of the lead screw 3 into the roller assembly 200, ensuring that the external thread 31 of the lead screw meshes correctly with the external thread 21 of the rollers. Then, install the other six planetary gears 24 at the other end of this roller assembly 200, and have them mesh with another gear ring 13. Install the nut front push rod seat 171 or the roller retaining ring 28 and the wire retaining ring 29 on the outside of the gear ring 13 of the roller assembly 200 to axially lock the roller assembly 200 relative to the nut 1.

[0146] See Figure 3 Each planetary gear 24 meshes with the corresponding gear ring 13, which is fixedly installed at the two ends of the nut 1 and circumferentially fixed relative to the nut 1.

[0147] When the device is running, the motor drives the lead screw 3 to rotate through the spline rod 8. According to the known transmission principle of planetary roller lead screws, the lead screw 3 will move axially under the thread drive of the roller assembly 200-1, and drive the roller assembly 200-2 to move axially at a speed of multiple times, and drive the push rod head 172 at the front end of the nut to apply a push or pull force to the outside.

[0148] Because the internal thread section of nut 1 and the external thread section of lead screw 3 are always between the cages 4 at both ends of the roller assembly during operation, the threads of nut 1, roller 2, and lead screw 3 do not contact the tooth profile of planetary gear 24. Therefore, the ends of the rollers do not require complex tooth profile and thread mixing machining as in existing technologies, significantly simplifying the machining difficulty of the rollers. Furthermore, the planetary gear can be manufactured efficiently and with high precision using existing mature technologies and processes, and then assembled later. Figure 5 As can be seen from the assembly method, the design and implementation of a fully automated assembly line for roller assemblies is not difficult.

[0149] In this embodiment, the internal thread length of the nut is set to 6cm, and the inner diameter of the nut is set to 3cm. With such a small length-to-diameter ratio, its processing difficulty is obviously much lower than that of existing similar products, and its production efficiency is also much higher.

[0150] The working stroke in this embodiment is 9cm. Obviously, the stroke can be changed by altering the length of the roller and the lead screw thread.

[0151] The power mechanisms described in the embodiments of this article are all frameless motors commonly used in similar devices. Obviously, depending on the needs and limitations of various application environments and performance parameters, other suitable power mechanisms, such as coreless motors, can also be used.

[0152] Example 2 Figures 6 to 9 As shown. Example assembly 9-2 is as follows. Figure 6 As shown in the middle figure.

[0153] See Figure 6 This embodiment has three outer shells, including two main outer shells 5-1 and 5-2 with an inner spline type 51 and an auxiliary outer shell section 55 with a motor stator coil group 61 in the inner cavity.

[0154] Each of the two main housings 5-1 and 5-2 contains a nut 1-1 and a nut 1-2, respectively. Each nut 1-1 and 1-2 is connected to a nut extension tube 12-1 and a nut extension tube 12-2. The outer cylindrical surface of each nut extension tube 12-1 and 12-2 is provided with an external spline 124. The mating splines fix the nut circumferentially relative to the main housing and allow it to move axially.

[0155] Each section of the nut extension tube 12-1 and 12-2 is equipped with a nut extension tube front connector 123 that serves as the power output end.

[0156] The two nuts 1-1 and 1-2 have opposite internal threads. Nut 1-1, which has a left-hand internal thread, contains a set of rollers 200-1 with a right-hand external thread; nut 1-2, which has a right-hand internal thread, contains a set of rollers 200-2 with a left-hand external thread.

[0157] There are two lead screws 3 of equal length. The external thread 31-1 of one lead screw 3-1 is left-handed, and the external thread 31-2 of the other lead screw 3-2 is right-handed.

[0158] See Figure 7 The external thread of the lead screw 3-1 with a left-hand thread is screwed into the roller assembly 200-1 inside the nut 3-1 with a right-hand thread. The external thread of the lead screw 3-2 with a right-hand thread is screwed into the roller assembly 200-2 inside the nut 3-2 with a left-hand thread.

[0159] See Figure 8 , Figure 9Each roller 2 has cylindrical end necks 22 at both ends with a diameter smaller than its thread minor diameter, and the cylindrical end necks 22 have end neck flat surfaces 221. Cages 4w and sun gears 32 are pre-installed at the two ends of the lead screw external thread 31. Cages 4w have six retaining holes 41 evenly distributed around the central bore. Each retaining hole 41 has an outward-facing notch 411. Each retaining hole 41 is equipped with an end sleeve 23. The outer diameter of the end sleeve 23 is the same as the diameter of the retaining hole 41, and the inner diameter of the end sleeve 23 is the same as the diameter of the cylindrical end necks 22 of the roller 2.

[0160] When installing rollers 2, each roller 2 must be inserted through the central hole of the cage 4, ensuring that the external thread 21 of the roller 2 meshes with the external thread 31 of the lead screw in the correct phase. Then, move the cylindrical end necks 22 at both ends of the roller 2 into the retaining holes 41 through the outward-facing notches 411. Next, place the end sleeve 23 over the cylindrical end necks 22 of the roller 2 and then insert it into the retaining holes 41 of the cage 4, preventing the roller 2 from dislodging from the retaining holes 41. The other rollers 2 are installed in the same manner.

[0161] Next, six planetary gears 24 are fitted onto one end of the cylindrical neck 22 of each roller 2 with an interference fit, and mesh with the corresponding sun gear 32. The flat surface 221 of the cylindrical neck 22 matches the flat surface inside the planetary gear 24 to keep the roller 2 and the planetary gear 24 circumferentially fixed. The pitch circle of the planetary gear 24 is equal to the thread pitch diameter of the roller 2.

[0162] After installing the six planetary gears 24 at one end of the roller assembly 200, screw the internal thread of the corresponding nut 1 into the roller assembly 200. Then, install the other six planetary gears 24 at the other end of the roller assembly 200 and mesh them with another sun gear 32. See also Figure 6 , Figure 7 A front roller limiting ring 26 is installed at the front end of the roller assembly 200, and a rear roller assembly bearing housing 2001 is installed at the rear end. The extension segments 33-1 and 33-2 of the two lead screws 3-1 and 3-2 are inserted into the spline hole 623 of the motor rotor base tube 621 between the two rear roller assembly bearing housings 2001. The two rear roller assembly bearing housings 2001 are fixedly connected to the lead screw extension segments 33 and the secondary housing segment 55 via positioning holes, thus restricting the axial fixation of the motor rotor base tube 621 relative to the secondary housing segment 55.

[0163] Clearly, in principle, this embodiment is a special application of reverse roller screw drive technology. It has two special features: First, the two screws 3-1 and 3-2 are axially fixed and can only rotate circumferentially. Second, the two nuts 1-1 and 1-2 are circumferentially fixed and cannot rotate, but can only move axially.

[0164] When the device is running, the motor located in the middle of the device drives the two lead screws 3-1 and 3-2 to rotate synchronously, at the same speed and in the same direction through the two nut extension tubes 12. The screws rotate in opposite directions, causing the two nuts 1-1 and 1-2 to move in opposite directions, and the extension and retraction power is output to the outside through the front end joints 123 of the two nut extension tubes.

[0165] Similar to Example 1, since the internal thread section of nut 1 and the external thread section of lead screw 3 are always between the cages 4 at both ends of the roller assembly during operation, the threads of nut 1, roller 2, and lead screw 3 will not contact the tooth profile of planetary gear 24. Therefore, complex tooth profile and thread mixing machining is not required at the ends of the rollers. However, to facilitate both the later assembly of nut 1 and the pre-installation of cages 4, the sun gear 32 located outside the two cages 4 should be a separately machined independent part, and should be fixedly installed on the lead screw 3 after the cages 4 are installed in place. Of course, a positioning structure should be adopted to ensure that the installed sun gear 32 is at the correct phase angle.

[0166] In this embodiment, both the internal thread length and the inner diameter of the nut are set to 3cm. The 1:1 length-to-diameter ratio allows the machining and grinding of its internal thread to be completed efficiently using general-purpose equipment.

[0167] Example 3 Figure 10 , Figure 11 As shown. Example assembly 9-3 is as follows. Figure 10 As shown in the middle figure.

[0168] This embodiment comprises an irregularly shaped tubular main outer shell 5, with a secondary outer shell section 55 at the right end of the main outer shell 5 containing the motor stator coil assembly 61. Inside the main outer shell 5 is a long tubular nut outer base cylinder 100. The front and rear ends of the nut outer base cylinder 100 are fitted with a front sealing ring 181 and a rear sealing ring 182. The front sealing ring 181 and the rear sealing ring 182 are respectively connected to both ends of the main outer shell 5 via bearings 7, thereby fixing the nut outer base cylinder 100 axially and allowing it to rotate circumferentially.

[0169] The outer base cylinder 100 of the nut is equipped with a ring of motor rotor magnets 62 on the cylindrical surface of the rear section, and the inner cavity is provided with the inner spline 102 of the outer base cylinder of the nut.

[0170] The outer base cylinder 100 contains three nuts: 1-3, 1-2, and 1-1 (left, center, and right). The left nut 1-3 and the center nut 1-2 are connected by threads. Each of the three nuts 1-3, 1-2, and 1-1 has an external spline type 14 that mates with the internal spline 102 of the outer base cylinder, thus fixing the three nuts 1-3, 1-2, and 1-1 circumferentially relative to the outer base cylinder 100.

[0171] The left-hand nut 1-3 and the middle nut 1-2, which are interconnected, are equipped with a left-hand roller assembly 200-2, while the right nut 1-1 is equipped with a right-hand roller assembly 200-1. The right-hand nut 1-1 is fixedly connected to the outer base cylinder 100 of the nut.

[0172] There are two lead screws, 3-2 and 3-1, on the left and right sides. The right end of the left lead screw 3-2 has a 3cm long left-hand external thread 31-3, and the front end 37 of the lead screw extension section on the left side of the left lead screw 3-2 is the power output end. The left end of the right lead screw 3-1 has a 3cm long right-hand external thread 31-2, and the right end has a 3cm long left-hand external thread 31-1. The axis of both lead screws 3-1 and 3-2 is a through spline hole 36. The diameter of the unthreaded lead screw extension section 33 and the middle section 38 of the lead screw is smaller than the minor diameter of the external thread 31 of the lead screw.

[0173] A splined rod 8 is fixed axially and passes through the spline hole 36 of the lead screw 3. The shape of the splined rod 8 matches the spline hole 36 of the lead screw 3. The splined rod 8 fixes the left and right lead screws 3-1 and 3-2 circumferentially, but allows them to move axially.

[0174] See Figure 11 The internal threads 11-3 of the left nut 1-3 and 11-1 of the right nut are left-handed, while the internal thread 11-2 of the middle nut 1-2 is right-handed. The internal thread length of all three nuts is 6cm.

[0175] Inside the left nut 1-3 and the middle nut 1-2, which are connected by screw threads, there is a set of rollers 200-2; the rollers 2-2 of the roller set 200-2 are 12cm long and include two external threads, one on the left and one on the right. The left 5.8cm external thread is left-handed and the right 5.8cm external thread is right-handed.

[0176] The right nut 1-1 contains another set of rollers 200-1. The roller 2-1 in the roller set 200-1 is 6cm long and its external thread is left-handed.

[0177] The left-hand external thread 31-3 of the lead screw 3-2 on the left screw position screws into the left section of roller assembly 200-2, engaging with the left-hand internal thread of roller 2-2 within roller assembly 200-2. The right-hand external thread 31-2 of the left section of the lead screw 3-1 on the right screw position screws into the right section of roller assembly 200-2, engaging with the right-hand internal thread of roller 2-2 within roller assembly 200-2. The left-hand external thread 31-1 of the right section of the lead screw 3-1 on the right screw position screws into the right-hand roller assembly 200-1, engaging with the left-hand internal thread of roller 2-1 within roller assembly 200-1.

[0178] The assembly method of the rollers 2, cages 4, end sleeves 23, planetary gears 24, and gear rings 13 in the two roller sets 200 is the same as in Example 1, see [link to example]. Figure 4 , Figure 5 .

[0179] The rear end of the spline rod 8 is fixedly connected to the rear port 53 of the main housing 5 by a spline rod tail pin 81.

[0180] During operation, the motor drives the outer base cylinder 100 of the nut and the three nuts 1 to rotate together. Based on the known transmission principle of a standard planetary roller screw, the two screws 3-1 and 3-2, as well as the left nut 1-3 and the middle nut 1-2, undergo axial movement, applying a pushing or pulling force to the outside through the front end 37 of the screw extension section. The maximum leftward movement of the right-hand screw 3-1 is 3 cm. Through a multiplication effect, the maximum leftward stroke of the left-hand screw is 9 cm.

[0181] In this embodiment, the internal thread length of all three nuts is set to 5cm, and the inner diameter of the nuts is set to 3cm. Obviously, the left nut 1-3 and the middle nut 1-2 can also be machined together.

[0182] Example 4 Figure 12 , Figure 13 As shown. Example assembly 9-4 is as follows. Figure 12 As shown in the middle figure.

[0183] This embodiment comprises an irregularly shaped tubular main outer shell 5, with a secondary outer shell section 55 at the right end of the main outer shell 5 containing a motor stator coil assembly 61 within its inner cavity. Inside the main outer shell 5 is a long tubular nut-shaped outer base cylinder 100. A front port cover 522 and a rear port cover 532 are respectively installed at the front port 52 and rear port 53 of the main outer shell 5, with the flat surfaces 521 and 531 of the front and rear ports ensuring circumferential fixation of the two covers.

[0184] The front and rear ends of the outer base cylinder 100 of the nut are mounted between the front end cover 522 and the rear end cover 532 of the outer casing via bearings 7 to maintain axial fixation.

[0185] A ring of motor rotor magnets 62 is mounted on the cylindrical surface of the rear section of the nut outer base cylinder 100. Two nuts 1-2 and 1-1, separated and positioned by a nut spacer 15, are fixedly installed inside the nut outer base cylinder 100. A roller assembly 200 is mounted within both nuts 1-2 and 1-1. The internal thread 11-2 of the left nut 1-2 is left-handed, and the internal thread 11-1 of the right nut is right-handed. The internal thread length of both nuts is 6 cm.

[0186] There are two lead screws, 3-2 and 3-1, on the left and right sides. The right end of the left lead screw 3-2 has a 3cm long left-hand external thread 31-2, and the left end of the right lead screw 3-1 has a 3cm long right-hand external thread 31-1. The diameter of the unthreaded lead screw extension segment 33 is smaller than the minor diameter of the lead screw external thread 31. The lead screw extension segments 33 of the left and right lead screws 3-2 and 3-1 respectively pass through the central holes 5221 and 5321 of the front and rear covers of the outer casing. Under the action of the flat surface 331 of the lead screw extension segment, the flat surface 5222 of the central hole of the front cover, and the flat surface 5322 of the central hole of the rear cover, they remain circumferentially fixed and can only move axially.

[0187] See Figure 13 The roller 2 of roller assembly 200 is 18cm long and includes two external threads, left and right. The left section, about 9cm long, has a left-hand thread 21-2, and the right section, about 9cm long, has a right-hand thread 21-1.

[0188] The left-hand external thread 31-2 of the right section of the lead screw 3-2 on the left is screwed into the left section of the roller assembly 200, engaging with the left section of the left-hand internal thread of the roller 2 within the roller assembly 200. The right-hand external thread 31-1 of the left section of the lead screw 3-1 on the right is screwed into the right section of the roller assembly 200, engaging with the right section of the right-hand internal thread of the roller 2 within the roller assembly 200.

[0189] The assembly method of the rollers 2, cage 4, end sleeve 23, planetary gear 24, and gear ring 13 in roller assembly 200 is the same as in embodiment 1, see [link to embodiment 1]. Figure 4 , Figure 5 Furthermore, when installing the roller 2, the roller groove ring 25 in the middle of the roller 2 must be inserted from the sub-frame notch 4211 of the sub-frame 42 pre-installed in the outer base cylinder 100 of the nut into the retaining hole 421 of the sub-frame. It should be noted that the sub-frame 42 is only an optional auxiliary part for the bending resistance and positioning of the roller 2.

[0190] During operation, the motor drives the outer base cylinder 100 of the nut and the two nuts 1 to rotate together. Based on the known transmission principle of a standard planetary roller screw, the two screws 3-1 and 3-2 generate opposite axial speeds, and apply a pushing or pulling force to the outside through the front ends 37 of the two screw extension sections. The stroke of the device is 9 cm.

[0191] Example 5 Figures 14 to 16 As shown. Example assembly 9-5 is as follows. Figure 14 As shown in the middle figure.

[0192] See Figure 14 , Figure 15The configuration of this embodiment includes an irregularly shaped tubular main outer shell 5, and a movable secondary outer shell section 55 is fitted at the right end of the main outer shell 5. The right part of the inner cavity of the secondary outer shell section 55 is equipped with a motor stator coil group 61.

[0193] The left side of the inner cavity of the secondary outer shell section 55 has a cup-shaped nut outer base cylinder 100. The inner wall of the nut outer base cylinder 100 has an inner spline 102. The right end of the nut outer base cylinder 100 is connected to the motor rotor base tube 621. The left section of the nut outer base cylinder 100 contains a long tubular double nut assembly 19, which consists of a left nut 1-2, a right nut 1-1, and a nut extension tube 12 connecting the left and right nuts. The outer spline 124 of the nut extension tube matches the inner spline 102 of the nut outer base cylinder, keeping the assembly of the two nuts circumferentially fixed and allowing it to move along the axis.

[0194] The motor rotor base tube 621 is axially fixed to the secondary housing section 55 by means of front and rear end bearings 7, and can rotate circumferentially. A ring of motor rotor magnets 62 is mounted on the outer cylindrical surface of the motor rotor base tube 621.

[0195] The internal thread 11-2 of the left nut 1-2 is left-handed, while the internal thread 11-1 of the right nut is right-handed. The internal thread length of both nuts is 3cm.

[0196] There are two lead screws, 3-2 and 3-1, on the left and right sides. The right end of the left lead screw 3-2 has a 7cm long left-hand external thread 31-2, and the left end of the right lead screw 3-1 has a 7cm long right-hand external thread 31-1. The diameter of the unthreaded extension segments 33-2 and 33-1 of the lead screws is smaller than the minor diameter of the external thread 31. The extension segments 33-2 and 33-1 of the left and right lead screws 3-2 and 3-1 respectively pass through the front port 52 of the main housing 5 and the rear end hole 551 of the auxiliary housing segment.

[0197] The lead screw extension segment 33-2 of the left-hand lead screw 3-2 extends from the front port 52 of the main housing 5 and is fixedly connected to the main housing 5 through the lead screw extension segment positioning hole 333 and the housing positioning pin hole 54. The lead screw extension segment 33-1 of the right-hand lead screw 3-1 is fixedly connected to the rear end hole 551 of the auxiliary housing segment.

[0198] The spline rod 8, which is fixed in the central hole of the lead screw 3-1, is inserted into the spline hole of the lead screw 3-2 on the left, so that the two lead screws are circumferentially fixed to each other.

[0199] See Figure 16 The length of roller 2 in both the left-hand roller group 200-2 and the right-hand roller group 200-1 is 7cm. The external thread of roller 2-2 in the left-hand roller group 200-2 is right-handed. The external thread of roller 2-1 in the right-hand roller group 200-1 is left-handed.

[0200] The left-hand external thread 31-2 of the lead screw 3-2 on the left is screwed into the left roller assembly 200-2; the right-hand external thread 31-1 of the lead screw 3-1 on the right is screwed into the right roller assembly 200-1.

[0201] The assembly method of the rollers 2, cages 4w, end sleeves 23, and sun gear 32 pre-mounted on the lead screw 3 in the two roller sets 200-1 and 200-2 is the same as in Example 2, see [link to example]. Figure 8 , Figure 9 .

[0202] During operation, the motor drives the outer base cylinder 100 of the nut and the double nut assembly 19 to rotate. Based on the known transmission principle of a reverse planetary roller screw, the left screw 3-2 can generate axial double-speed movement and apply a pushing or pulling force to the outside through its extended rod end 37-2. The axially moving left screw 3-2 drives the main housing 5 to slide synchronously along the secondary housing section 55. The stroke of the device is 9 cm.

[0203] Example 6 Figure 17 , Figure 18 As shown. Example assembly 9-6 is as follows. Figure 17 As shown in the middle figure.

[0204] This embodiment includes a tubular main housing 5, with a motor stator coil assembly 61 housed in the inner cavity of the right section of the main housing 5. Inside the main housing 5 is a long tubular nut-shaped outer base cylinder 100. A front port cover 522 and a rear port cover 532 are respectively installed at the front and rear ports of the main housing 5.

[0205] The front end of the outer base tube 100 is connected to the inner cavity of the front port cover 522 of the outer casing via the front sealing ring 181 and bearing 7. The rear end of the outer base tube 100 is connected to the inner cavity of the rear port cover 532 of the outer casing via the rear sealing ring 182, the motor rotor base tube 621, and bearing 7. The motor rotor base tube 621 is externally fitted with a motor rotor magnet assembly 62.

[0206] Two nuts, 1-2 and 1-1, are installed between two nut spacers 15 and a sub-frame 42 inside the outer base cylinder 100 of the nut. The two nuts are fixed inside the outer base cylinder 100 of the nut by the nut positioning pin hole 16 and the nut outer base cylinder positioning pin hole 103.

[0207] Both nuts 1-2 and 1-1 on the left and right sides share a roller assembly 200. The internal thread 11-2 of the left nut 1-2 is left-handed, while the internal thread 11-1 of the right nut is right-handed. The internal thread length of both nuts is 5cm.

[0208] There are two lead screws, 3-2 and 3-1, on the left and right sides. The right end of the left lead screw 3-2 has a 3cm long left-hand external thread 31-2, and the left end of the right lead screw 3-1 has a 3cm long right-hand external thread 31-1. The diameter of the unthreaded lead screw extension segment 33 is smaller than the minor diameter of the lead screw external thread 31. The lead screw extension segments 33 of the left and right lead screws 3-2 and 3-1 respectively pass through the central holes 5221 and 5321 of the front and rear covers of the outer casing. Under the action of the flat surface 331 of the lead screw extension segment, the flat surface 5222 of the central hole of the front cover, and the flat surface 5322 of the central hole of the rear cover, they remain circumferentially fixed and can only move axially.

[0209] The roller 2 of roller assembly 200 is 15cm long and includes two external threads, left and right. The left section, about 7.5cm long, has a left-hand thread 21-2, and the right section, about 7.5cm long, has a right-hand thread 21-1.

[0210] The left-hand external thread 31-2 of the right section of the lead screw 3-2 on the left is screwed into the left section of the roller assembly 200, engaging with the left section of the left-hand internal thread of the roller 2 within the roller assembly 200. The right-hand external thread 31-1 of the left section of the lead screw 3-1 on the right is screwed into the right section of the roller assembly 200, engaging with the right section of the right-hand internal thread of the roller 2 within the roller assembly 200.

[0211] The assembly method of the rollers 2, cage 4, end sleeve 23, planetary gear 24, and gear ring 13 in roller assembly 200 is the same as in embodiment 1, see [link to embodiment 1]. Figure 4 , Figure 5 Furthermore, when installing the roller 2, the roller groove ring 25 in the middle of the roller 2 must be inserted from the sub-frame notch 4211 of the sub-frame 42 pre-installed in the outer base cylinder 100 of the nut into the retaining hole 421 of the sub-frame. It should be noted that the sub-frame 42 is only an optional auxiliary part for the bending resistance and positioning of the roller 2.

[0212] During operation, the motor drives the outer base cylinder 100 of the nut and the two nuts 1 to rotate together. Based on the known transmission principle of a standard planetary roller screw, the two screws 3-1 and 3-2 generate opposite axial relative speed movements, and apply pushing and pulling forces externally through the front ends 37-2 and 37-1 of the two screw extension sections. The stroke of the device is 9 cm.

[0213] Example 7 Figure 19 , Figure 20 As shown. Example assembly 9-7 is as follows. Figure 19 As shown in the middle figure.

[0214] This embodiment comprises an irregularly shaped tubular main housing 5. The right section of the main housing 5 consists of a first auxiliary housing section 55-1 containing the first turn of the motor stator coil assembly 61-1 and a slightly larger diameter second auxiliary housing section 55-2 containing the second turn of the motor stator coil assembly 61-2. Inside the main housing 5 is a long tubular nut-shaped outer base cylinder 100. A front port cover 522 is fixedly installed at the front port 52 of the main housing 5. The rear port 53 is connected to the right shaft seat of the rear port cover 532 via a bearing 7-1.

[0215] The front end of the outer base tube 100 is mounted on the right shaft seat of the front port cover 522 of the housing via bearing 7-3, and the rear end of the outer base tube 100 is mounted on the left shaft seat of the rear port cover 532 of the housing via bearing 7-2. The rear port cover 532 of the housing is fixedly connected to the right end of a motor rotor base tube 621. The first coil of motor rotor magnet assembly 62-1 is mounted on the cylindrical surface of the middle section of the outer base tube 100, and its position is aligned with the first coil of motor stator coil assembly 61-1. The right section of the outer base tube 100 is inserted into the motor rotor base tube 621. The second coil of motor rotor magnet assembly 62-2 is mounted on the outer cylindrical surface of the motor rotor base tube 621, and is aligned with the second coil of motor stator coil assembly 61-2.

[0216] Four nuts 1-1, 1-2, 1-3, and 1-4, separated by multiple nut spacers 15 and positioned by locating pin holes 103 on the outer base cylinder of the nut, are fixedly installed inside the outer base cylinder 100. The two left-hand nuts 1-4 and 1-3 share a left-hand roller assembly 200-2. The two right-hand nuts 1-2 and 1-1 share a right-hand roller assembly 200-1. The internal threads of the two left-hand nuts 1-4 and 1-3 are left-handed, while the internal threads of the two right-hand nuts 1-2 and 1-1 are right-handed. The internal thread length of each nut is 3.5 cm.

[0217] There are two lead screws, 3-2 and 3-1, on the left and right sides. The right end of the left lead screw 3-2 has a 4.5cm long left-hand external thread 31-2, and the left end of the right lead screw 3-1 has a 4.5cm long right-hand external thread 31-1. The diameter of the lead screw extension segments 33-2 and 33-1 is smaller than the minor diameter of the external thread 31. The lead screw extension segment 33-2 of the left lead screw 3-2 passes through the central hole 5221 of the front cover of the outer casing. The lead screw extension segment 33-1 of the right lead screw 3-1 has a flat surface 331. The splined rod 8, fixed to the axis of the left lead screw 3-2, is inserted into the splined hole of the right lead screw 3-1, so that the two lead screws 3-2 and 3-1 are circumferentially fixed to each other and can move axially relative to each other. The lead screw extension segment 33-1 of the right lead screw 3-1 is inserted into the central hole 5321 of the housing rear cover, and the right lead screw 3-1 is circumferentially fixed relative to the motor rotor base tube 621 under the constraints of the flat surface 331 of the lead screw extension segment and the flat surface 5322 of the central hole of the housing rear cover.

[0218] The front ends 37-1 and 37-2 of the lead screw extension segments of the left and right lead screws 3-2 and 3-1 adopt a connection structure that can maintain circumferential freedom and axial fixation with the lead screw, such as ball joint connection.

[0219] The length of roller 2 in each roller group 200 is 9cm. The external thread 21-2 of the roller in the left roller group 200-2 is left-handed; the external thread 21-1 of the roller in the right roller group 200-1 is right-handed.

[0220] The left-hand external thread 31-2 on the right section of the lead screw 3-2 on the left is screwed into the left roller assembly 200-2. The right-hand external thread 31-1 on the left section of the lead screw 3-1 on the right is screwed into the right roller assembly 200-1.

[0221] The assembly method of the rollers 2, cages 4, end sleeves 23, planetary gears 24, and gear rings 13 in the two roller sets 200 is the same as in Example 1, see [link to example]. Figure 4 , Figure 5 .

[0222] When the device is running, if only the first frameless motor is activated, it will drive the outer base cylinder 100 of the nut and the four nuts 1 to rotate together. If only the second frameless motor is activated, it will drive the two lead screws 3 to rotate, causing the two lead screws 3-1 and 3-2 to move axially at opposite speeds, and applying a push-pull force to the front ends 37 of the two lead screw extension sections. The stroke of the device is 9 cm. It is easy to understand that when both motors are activated and operate with independent speed changes and reversals, the positive effects described above will be produced.

[0223] 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 fast planetary roller screw drive device, comprising a nut placed inside a main housing, multiple rollers inserted into the nut, and a screw surrounded by the rollers; the external threads of the rollers mesh with the external threads of the screw and with the internal threads of the nut; cages are inserted into both ends of the rollers; when the device is running, the screw and the nut rotate relative to each other under the drive of the power mechanism. Its characteristics are: Including lead screws with left-hand external threads; Including lead screws with right-hand external threads; This includes nuts with left-hand internal threads; This includes nuts with right-hand internal threads; Including rollers with left-hand external threads; Including rollers with right-hand external threads; A lead screw with a left-hand external thread is circumferentially fixed relative to a lead screw with a right-hand external thread; A nut with a left-hand internal thread is circumferentially fixed relative to a nut with a right-hand internal thread.

2. The rapid planetary roller screw transmission device according to claim 1, characterized in that: The nuts include a left-handed nut and a right-handed nut; these two nuts are circumferentially fixed relative to the housing; one nut is axially movable along the housing and one end of it is connected to a working push rod; the other nut is fixedly connected to the housing. A nut with a left-hand internal thread contains a set of rollers with a left-hand external thread. A nut with a right-hand internal thread contains a set of rollers with a right-hand external thread. The lead screw has a spline hole as its axis. The lead screw has a left-hand external thread and a right-hand external thread. The left-hand external thread of the lead screw is screwed into the roller assembly inside the nut with the left-hand internal thread, and the right-hand external thread of the lead screw is screwed into the roller assembly inside the nut with the right-hand internal thread. There is an axially fixed spline rod that passes through the spline hole of the aforementioned lead screw; The power mechanism drives the spline rod to rotate, and the spline rod in turn drives the lead screw to rotate.

3. The high-speed planetary roller screw transmission device according to claim 1, characterized in that: The nuts include a left-handed nut and a right-handed nut; these two nuts are circumferentially fixed relative to the housing and are axially movable along the inner cavity of the housing. A nut with a left-hand internal thread contains a set of rollers with a right-hand external thread. A nut with a right-hand internal thread contains a set of rollers with a left-hand external thread. There are two axially fixed lead screws, one of which has a left-hand thread and the other has a right-hand thread. The external thread of a lead screw with a left-hand thread is screwed into the roller assembly inside a nut with a right-hand thread, and the external thread of a lead screw with a right-hand thread is screwed into the roller assembly inside a nut with a left-hand thread. The two lead screws are driven and rotated by the power mechanism located in the middle of the housing.

4. The rapid planetary roller screw transmission device according to claim 1, characterized in that: It includes three nuts distributed on the left, center and right, which are fixed circumferentially relative to the outer shell; The nut in the middle is fixedly connected to the nut on the right and can move along the axial direction of the outer casing; The nut on the left is fixedly connected to the left side of the outer casing; The internal thread of the middle nut has the opposite direction of rotation to the internal threads of the other two nuts; Each of the three nuts contains a set of rollers, and the internal thread of each nut is in the same direction as the external thread of the roller inside the nut. Includes two lead screws, one on the left and one on the right, both of which have spline holes; The lead screw on the left has two sections of external threads with opposite directions of rotation. The direction of rotation of the left section of external thread is the same as that of the internal thread of the left nut; the direction of rotation of the right section of external thread is the same as that of the internal thread of the nut in the middle. The left-hand section of the lead screw's external thread is screwed into the roller assembly inside the left-hand nut, and the right-hand section of the lead screw's external thread is screwed into the roller assembly inside the middle nut. The right-hand lead screw has an external thread on its left side, which screws into the roller assembly inside the right-hand nut. The direction of the external thread on the left side of the right-hand lead screw is the same as the direction of the internal thread on the right-hand nut. The right end of the lead screw on the right extends from the hole on the right end of the housing; There is a splined rod whose left end is fixedly connected to the outer casing, and the splined rod passes through the spline hole of the aforementioned lead screw; The power mechanism drives each nut to rotate and causes the two lead screws to move axially.

5. The high-speed planetary roller screw transmission device according to claim 1, characterized in that: It includes two nuts, one on the left and one on the right, which are fixedly connected to each other and axially fixed relative to the outer casing; The internal thread of the nut on the left has the opposite direction of rotation to that of the nut on the right. The rollers with left-hand external threads and the rollers with right-hand external threads are located in different nuts; The internal thread of each nut is in the same direction as the internal thread of the roller located therein; It includes two lead screws, one on the left and one on the right; these two lead screws are fixed circumferentially relative to the housing and can move axially along the housing. The right side of the lead screw on the left has an external thread, and the left side of the lead screw on the right has an external thread. The external threads of the left and right lead screws rotate in opposite directions; The external thread of the lead screw on the left is screwed into the roller assembly inside the nut on the left. The external thread of the right-hand lead screw is screwed into the roller assembly inside the right-hand nut; The power mechanism drives each nut to rotate and causes the two lead screws to move in opposite directions along the axial direction.

6. The rapid planetary roller screw transmission device according to claim 1, characterized in that: It includes two nuts, one on the left and one on the right, which are fixedly connected to each other; The internal thread of the nut on the left has the opposite direction of rotation to that of the nut on the right. The rollers with left-hand external threads and the rollers with right-hand external threads are respectively inserted into different nuts; The internal thread of the nut on the left has the same direction of rotation as the external thread of the roller inside it; The internal thread of the nut on the right has the same direction of rotation as the external thread of the roller inside it; It includes two lead screws, one on the left and one on the right, which are fixed circumferentially relative to the outer casing; wherein, the lead screw on the left can move axially along the outer casing, and the right end of the lead screw on the right is fixedly connected to the right end of the outer casing. The right side of the lead screw on the left has an external thread, and the left side of the lead screw on the right has an external thread. The external threads of the left and right lead screws rotate in opposite directions; The external thread of the lead screw on the left is screwed into the roller assembly inside the nut on the left. The external thread of the right-hand lead screw is screwed into the roller assembly inside the right-hand nut; The power mechanism drives each nut to rotate.

7. The rapid planetary roller screw transmission device according to claim 2 or 3, characterized in that: The total length of the external threads of each lead screw shall not be greater than the total length of the external threads of the roller around which the lead screw is surrounded; The total length of the external threads of each roller is not less than the total length of the internal threads of the nut around which the roller is surrounded; The total length of the external threads of each lead screw is not equal to the total length of the internal threads of the nut around which the lead screw is wrapped; Each roller has a cylindrical neck at both ends inserted into the inner hole of a circular end sleeve, which can be inserted into a retaining hole of the same diameter as the cage. The hole should have an outward notch, the width of which is less than the outer diameter of the end sleeve and greater than the inner diameter of the end sleeve. The cylindrical end neck of each roller passes through the inner hole of an end sleeve, then through the middle hole of a planetary gear, and is fixedly connected to the planetary gear. The pitch circle of a planetary gear is equal to the thread pitch diameter of a roller. The lead screw has sun gears at both ends of its external thread, and each sun gear meshes with a corresponding planetary gear.

8. The rapid planetary roller screw transmission device according to any one of claims 4 to 6, characterized in that: The total length of the external threads of each lead screw shall not be greater than the total length of the external threads of the roller around which the lead screw is surrounded; The total length of the external threads of each roller is not less than the total length of the internal threads of the nut around which the roller is surrounded; The total length of the external threads of each lead screw is not equal to the total length of the internal threads of the nut around which the lead screw is wrapped; Each roller has a cylindrical neck at both ends inserted into the inner hole of a circular end sleeve, which can be inserted into a retaining hole of the same diameter as the cage. The hole should have an inward notch, the width of which is smaller than the outer diameter of the end sleeve and larger than the inner diameter of the end sleeve. The cylindrical end neck of each roller passes through the inner hole of an end sleeve, then through the middle hole of a planetary gear, and is fixedly connected to the planetary gear. The pitch circle of a planetary gear is equal to the thread pitch diameter of a roller. The outer side of the cage has toothed rings, each of which meshes with a corresponding planetary gear; Each toothed ring is circumferentially fixed relative to the nut.

9. The rapid planetary roller screw transmission device according to any one of claims 1 to 6, characterized in that: Includes a second power mechanism that can drive the lead screw to rotate; The second power mechanism can operate independently.

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