Planetary roller screw pair

Abstract

The invention relates to the field of planetary roller lead screws, in particular to a planetary roller lead screw pair which comprises a lead screw, the lead screw is sleeved with a shell, planet carriers are rotationally connected to the two ends of the shell, a plurality of threaded rollers are rotationally installed between the planet carriers at the two ends, one side of each threaded roller is in threaded connection with the inner wall of the shell, and the other side of each threaded roller is in threaded connection with the inner wall of the shell. The other side of the threaded roller is in threaded connection with the lead screw, the middle of the threaded roller is a polished shaft, and a fixing frame is arranged in the shell. The sliding block is pushed to move through centrifugal force generated when the round block plate rotates at a high speed, the sliding block pushes the push rod to move through the connecting piece, the push rod pushes the balls to abut against the threaded pin rollers below, the threaded pin rollers are prevented from moving due to the centrifugal force, and thread disengaging generated after the threaded pin rollers and the lead screw run for a long time is avoided; the service life of the planetary roller lead screw is guaranteed, and potential safety hazards generated when the planetary roller lead screw operates are avoided.

Description

Technical Field

[0001] This invention relates to the field of planetary roller screws, specifically a planetary roller screw pair. Background Technology

[0002] A lead screw assembly is a mechanical device that converts rotary motion into linear motion. There are several different types of lead screw assemblies, including sliding lead screw assemblies, ball screw assemblies, roller screw assemblies, and planetary roller screw assemblies. Among them, planetary roller screw assemblies have high load capacity, long life, high rigidity, high precision, and high-speed performance, and are commonly used in high-precision machine tools and aerospace equipment. The conversion between rotary and linear motion is achieved by multiple rollers rolling between the screw and the nut. The rollers both rotate on their own axis and revolve around a nut, similar to the motion of a planetary gear system. However, it is important to note that when the lead screw needs to run at high speed, the threaded rollers generate centrifugal force. This centrifugal force causes the threaded rollers to move towards the threaded grooves on the outer casing, away from the central lead screw. Over time, this can lead to the outer casing side... Severe wear of the threads can eventually lead to desiccation of the threaded rollers from the screw, significantly reducing the service life of the planetary roller screw pair. To address this issue, patent application CN115087820A provides a planetary roller screw that uses a preloading device to adjust the axial preload between the housing, screw, and threaded rollers, preventing excessive clearance from causing the threaded rollers to detach from the housing or screw. However, when planetary roller screw pairs are used in aerospace equipment or other devices where timely adjustment is not possible, desiccation is likely to occur during high-speed operation. Once desiccation occurs, the planetary roller screw pair will cease operation, ultimately posing a safety hazard to aerospace and other equipment. Summary of the Invention

[0003] The purpose of this invention is to provide a planetary roller screw assembly to solve the problem that the centrifugal force generated by the threaded rollers leads to accelerated wear and severely reduces the service life of the planetary roller screw assembly. At the same time, it also solves the safety hazard caused by the desiccation of the planetary roller screw assembly when it is used in aerospace equipment and other equipment that cannot be adjusted in a timely manner.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A planetary roller screw assembly includes a lead screw, a housing fitted onto the lead screw, planetary carriers rotatably connected to both ends of the housing, and multiple threaded rollers rotatably mounted between the two planetary carriers. One side of each threaded roller is threadedly connected to the inner wall of the housing, and the other side is threadedly connected to the lead screw. The middle portion of each threaded roller is a linear axis. A fixed frame is provided inside the housing, located at the linear axis of the threaded roller. A push rod is slidably connected to the fixed frame, and a ball is rolledly connected to one end of the push rod. A pushing assembly is provided inside the housing, abutting against the push rod. When the threaded roller rotates downwards or rotates rapidly, the pushing assembly pushes the threaded roller to move via the push rod and the ball on the push rod, causing the threaded roller to move closer to the central axis of the lead screw.

[0006] When a planetary roller screw operates, the motor drives the screw to rotate. Because multiple threaded rollers inside the housing are threadedly connected to the screw, the screw drives these rollers to rotate. Due to its planetary structure, these rollers also revolve around the central screw. The screw's helical structure allows it to move the meshing rollers. During normal, slow operation, the screw smoothly moves the rollers and housing. However, at high speeds, the screw drives the rollers to revolve, causing centrifugal force. This centrifugal force pushes the rollers towards the threaded grooves on the housing, away from the central screw. Over time, this can lead to wear and tear on one side of the housing. Severe wear occurs due to the threaded rollers being far from the central lead screw. This causes the contact area between the lead screw and the threaded rollers to remain at the tooth tip for extended periods. Prolonged operation wears down the tooth tip at the connection point, eventually leading to desiccation. Therefore, compensation is needed to ensure the threaded rollers remain in their original position during high-speed lead screw operation, preventing them from moving away from the lead screw. This is achieved by driving a push assembly during high-speed rotation of the threaded rollers. This push assembly moves a push rod, which in turn pushes a ball bearing against the lower threaded roller, preventing movement due to centrifugal force. This prevents desiccation after prolonged operation, ensuring the lifespan of the planetary roller lead screw and avoiding serious safety hazards.

[0007] Preferably, the pushing assembly includes a circular block frame, a limiting post, a sliding block, a first compression spring, short posts, telescopic rods, and a rotating block. The circular block frame is rotatably installed inside the housing and is sleeved on the lead screw. The circular block frame has multiple holes, and each threaded roller passes through a corresponding hole. The circular block frame has multiple through slots, and a limiting post is fixedly installed in each through slot. A sliding block is sleeved on the limiting post and slidably connected to the through slot. A first compression spring abuts against one side of the sliding block and the inner wall of the through slot. The first compression spring is sleeved on the limiting post. Two short posts are fixedly installed on the sliding block. Multiple telescopic rods are installed on the circular block frame, and a rotating block is rotatably connected to the circular block frame. The movable end of the telescopic rod is fixedly installed to the rotating block. One end of the telescopic rod is rotatably connected to a short post, and the other end of the telescopic rod is provided with a connector that abuts against a push rod. The fixing frame is fixedly installed between the two circular block frames.

[0008] When the threaded rollers rotate and revolve, they drive the circular block holder fitted on the threaded rollers to rotate simultaneously. Since the threaded rollers all pass through holes in the circular block holder, the rotation of the threaded rollers does not interfere with the circular block holder; the threaded rollers only drive the circular block holder to revolve. Therefore, during the high-speed rotation of the lead screw, it can drive the circular block holder to rotate at high speed simultaneously. The high-speed rotation of the circular block holder generates a corresponding centrifugal force according to the rotational speed. Thus, the sliding block sliding within the through groove of the circular block holder can move due to the generated centrifugal force. Simultaneously, the movement of the sliding block compresses the first compression spring abutting on one side, causing the first compression spring to contract. The movement of the sliding block drives the telescopic rod rotatably connected to the sliding block to move. The movable end of the telescopic rod maintains a relative rotational position with the circular block holder, causing the telescopic rod to form... The lever structure has a telescopic rod whose movable end is connected to a push rod via a connector. When the sliding block moves outward from the circular block frame due to centrifugal force, it pushes the push rod in the opposite direction through the telescopic rod and connector, moving it inward from the circular block frame. This pushes the threaded roller closer to the central screw. When the screw resumes low-speed operation, the centrifugal force generated by the rotation of the circular block frame cannot resist the squeezing force generated by the first compression spring. Therefore, the compressed first compression spring returns to its original position, causing the sliding block to return to its original position as well. Similarly, the telescopic rod of the lever structure returns to its original position as the sliding block returns to its original position. The centrifugal force generated by the rotation compensates for the threaded roller when the screw rotates at high speed, preventing the threaded roller from moving due to centrifugal force and preventing the threaded roller from desiccating after long-term operation, thus ensuring the service life of the planetary roller screw.

[0009] Preferably, the connecting component includes a push plate, a stabilizing column, a pressing block, and a rubber strip. The push plate is fixedly installed on the push rod. Stabilizing columns are provided on both sides of the push plate. The stabilizing columns slide on the fixed frame. Pressing grooves are provided on both sides of the push plate. Pressing blocks are slidably connected in the pressing grooves. The pressing blocks are connected to the push plate by screws. A rubber strip is placed in the pressing groove. The middle part of the rubber strip abuts against the pressing block. The two ends of the rubber strip are fixedly installed to the movable ends of the telescopic rods on both sides.

[0010] During equipment installation, the pressing block is opened with screws, the middle part of the rubber strip is placed in the center of the pressing groove, the pressing block is then placed over the rubber strip and secured with screws. Simultaneously, both ends of the rubber strip need to be fixed to the telescopic rods on both sides. When the sliding block pushes the telescopic rods to move in the opposite direction, the moving end of the telescopic rod stretches the rubber strip, generating a certain tension and pushing the push plate below. Both telescopic rods on both sides can compress the middle rubber strip, ensuring even force distribution on the push plate and allowing it to be driven by centrifugal force from both sides. The rubber strip generates thrust downwards, preventing excessive wear of the downward-moving push rod due to prolonged stress on the same side. It also prevents excessive movement of the sliding block, which could cause excessive compression of the push plate by the telescopic rod. Stabilizing columns on both sides of the push plate ensure stable up-and-down movement, preventing wobbling caused by prolonged rotation of the push plate by the circular block frame. The rotation generates centrifugal force to compensate for the threaded rollers during high-speed rotation of the screw, preventing movement of the threaded rollers due to centrifugal force and preventing desiccation of the threaded rollers and screw after prolonged operation, thus ensuring the lifespan of the planetary roller screw.

[0011] Preferably, the fixed frame has a circular hole for the push rod to slide, and the central axis of the circular hole is in the same plane as the central axis of the threaded roller and the lead screw. A second compression spring is sleeved on the push rod, and the two ends of the second compression spring abut against the push plate and the fixed frame, respectively.

[0012] The sliding of the push rod causes the ball to press against the threaded roller below, pushing the threaded roller closer to the lead screw. When the push rod pushes the threaded roller in any direction, the final position of the threaded roller pushed by the push rod is offset from the position of the lead screw. Therefore, by making the central axis of the circular hole, the central axis of the threaded roller, and the central axis of the lead screw all in the same plane, the push rod can always push the threaded roller straight towards the central axis of the lead screw during rotation. A second compression spring is set to prevent the threaded roller from not contacting the ball under normal operating conditions, thus avoiding long-term wear. It also prevents the ball from restricting the rotation of the threaded roller for a long time. By pushing the threaded roller to move when the lead screw rotates at high speed, the push rod prevents the threaded roller from moving due to centrifugal force, thus preventing the threaded roller from desiccating after long-term operation and ensuring the service life of the planetary roller screw.

[0013] Preferably, a limit block is fixedly installed on the sliding block, and a counterweight rod is rotatably connected between the two limit blocks. The counterweight rod is made of iron and has a teardrop-shaped cross-section.

[0014] It is important to note that because the threaded rollers are made of metal, their overall weight increases significantly. During high-speed rotation, the centrifugal force generated by the sliding block cannot suppress the centrifugal force generated by the threaded rollers, preventing the sliding block from pushing the threaded rollers towards the center. Increasing the weight of the sliding block can further enhance the centrifugal force it generates. Additionally, the counterweight rod has a teardrop-shaped cross-section. When it rotates around the lead screw at high speed, the teardrop head of the counterweight rod rotates outwards, further increasing the centrifugal force generated by the counterweight rod's rotation. Furthermore, the counterweight rod connects the sliding blocks on both sides, allowing them to move the same distance. This ensures that the force applied to the central push rod by the two telescopic rods is equal, preventing one side of the push rod from experiencing greater force than the other, thus avoiding accelerated wear and indirectly improving the service life of the planetary roller screw assembly.

[0015] Preferably, the side wall of the circular block frame is provided with a plurality of evenly arranged grooves. The cross-section of the groove is rectangular and the bottom of the groove is inclined upward. The outer shell is provided with lubricating oil. Because the threaded roller needs to rotate at high speed, the temperature of the lubricating oil at the corresponding position increases sharply, which seriously affects the service life of the planetary screw. Therefore, the high temperature lubricating oil below is scooped up through the groove and splashed onto the inner wall of the outer shell for cooling. Of course, the bottom of the groove is inclined upward to facilitate the upward scooping of lubricating oil.

[0016] Preferably, the circular block frame is evenly divided into four sector-shaped circular plates. Multiple through holes are provided on both sides of each sector-shaped circular plate. A locking frame is placed in the corresponding through hole of two adjacent sector-shaped circular plates. Multiple rotating columns are rotatably connected to the inner wall of the holes. When the threaded roller passes through the holes, it abuts against the rotating columns. Because the circular block frame needs to be fitted onto multiple threaded rollers, it is necessary to disassemble the circular block frame and then install it onto the threaded rollers respectively. Multiple locking frames are inserted into the through holes of the sector-shaped circular plates so that the circular block frame will not fall apart when the whole assembly rotates, thereby ensuring the service life of the planetary roller screw pair.

[0017] Preferably, an annular groove is formed on the inner wall of the outer casing, and the circular block frame is rotatably connected in the annular groove. A rubber ring is fixedly installed on the inner wall of the annular groove, and one side of the rubber ring abuts against the circular block frame. The annular groove restricts the rotation of the circular block frame, preventing it from deviating during rotation and causing it to jam and become unusable. Of course, the rubber ring on one side can also seal the lubricating oil scooped out of the annular groove, preventing the lubricating oil in the annular groove from leaking due to centrifugal force, thereby indirectly ensuring the service life of the planetary roller screw pair.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. The centrifugal force generated by the high-speed rotation of the circular plate drives the sliding block to move. The sliding block pushes the push rod to move through the connecting part, so that the push rod pushes the ball to abut against the threaded roller below. This prevents the threaded roller from moving due to centrifugal force, avoids the threaded roller from desiccating after long-term operation of the screw, ensures the service life of the planetary roller screw, and avoids safety hazards during the operation of the planetary roller screw.

[0020] 2. By aligning the central axis of the circular hole with the central axes of the threaded roller and the lead screw in the same plane, the push rod can consistently push the threaded roller in a straight line close to the central axis of the lead screw during rotation. This prevents the threaded roller from shifting to a different position from the lead screw when the push rod moves the threaded roller in any direction due to increased wear. This avoids the threaded roller moving and the lead screw still experiencing desiccation after long-term operation, ensuring the service life of the planetary roller lead screw and preventing safety hazards during its operation.

[0021] 3. By adding a counterweight rod, the centrifugal force generated by the sliding block can be increased. At the same time, the cross-section of the counterweight rod is teardrop-shaped. When it rotates around the lead screw, the teardrop head of the counterweight rod will rotate outward, which strengthens the centrifugal force generated by the rotation of the counterweight rod. This allows the connecting parts to move the threaded balls stably, avoids the threaded rollers from desiccating after long-term operation of the lead screw, ensures the service life of the planetary roller screw, and avoids safety hazards during the operation of the planetary roller screw. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0023] Figure 2 This is a three-dimensional structural diagram of the circular block frame in this invention;

[0024] Figure 3 This is a schematic diagram of the planar structure of the circular block frame in this invention;

[0025] Figure 4 for Figure 3 Enlarged structural diagram at point A;

[0026] Figure 5 This is a schematic diagram of the push plate structure in this invention;

[0027] Figure 6 This is a schematic diagram of the installation structure of the sector-shaped circular plate in this invention;

[0028] Figure 7 This is a schematic diagram of the structure of the sector-shaped circular plate in this invention.

[0029] In the diagram: 1. Lead screw; 2. Threaded roller; 3. Housing; 4. Circular groove; 5. Circular block frame; 501. Sector-shaped circular plate; 6. Through groove; 7. Sliding block; 8. Limiting post; 9. First compression spring; 10. Telescopic rod; 11. Short post; 12. Rotating block; 13. Counterweight rod; 14. Rubber strip; 15. Locking frame; 16. Fixing frame; 17. Push plate; 18. Stabilizing post; 19. Push rod; 20. Second compression spring; 21. Ball bearing; 22. Pressing groove; 23. Pressing block; 24. Rotating post; 25. Through hole; 26. Limiting block; 27. Hole; 28. Rubber ring; 29. ​​Groove. Detailed Implementation

[0030] Please see Figures 1 to 7 This invention provides a planetary roller screw pair, the technical solution of which is as follows:

[0031] A planetary roller screw pair, please refer to Figure 1 and Figure 5 The system includes a lead screw 1, a housing 3 fitted onto the lead screw 1, planetary carriers rotatably connected to both ends of the housing 3, and multiple threaded rollers 2 rotatably mounted between the two planetary carriers. One side of the threaded rollers 2 is threadedly connected to the inner wall of the housing 3, and the other side of the threaded rollers 2 is threadedly connected to the lead screw 1. The middle part of the threaded rollers 2 is an optical axis. A fixing frame 16 is provided inside the housing 3. The fixing frame 16 is located at the optical axis position of the threaded rollers 2. A push rod 19 is slidably connected to the fixing frame 16, and a ball bearing 21 is rotatably connected to one end of the push rod 19.

[0032] Please see Figure 1 , Figure 2 and Figure 3A circular block frame 5 is rotatably installed inside the outer casing 3. The circular block frame 5 is evenly divided into four sector-shaped circular plates 501. Multiple through holes 25 are opened on both sides of each sector-shaped circular plate 501. A locking frame 15 is placed in the corresponding through hole 25 of two adjacent sector-shaped circular plates 501. Multiple rotating columns 24 are rotatably connected to the inner wall of the hole 27. When the threaded roller 2 passes through the hole 27, it abuts against the rotating column 24. The circular block frame 5 is sleeved on the lead screw 1. The circular block frame 5 has multiple holes 27, and each threaded roller 2 passes through the corresponding hole 27. The circular block frame 5 has multiple holes 27. Multiple through slots 6 are provided, with limiting posts 8 fixedly installed inside each through slot 6. A sliding block 7 is fitted onto the limiting post 8 and is slidably connected inside the through slot 6. A first compression spring 9 is abutted between one side of the sliding block 7 and the inner wall of the through slot 6. The first compression spring 9 is fitted onto the limiting post 8. Two short posts 11 are fixedly installed on the sliding block 7. Multiple telescopic rods 10 are installed on the circular block frame 5. A rotating block 12 is rotatably connected to the circular block frame 5. The movable end of the telescopic rod 10 is fixedly installed with the rotating block 12, and one end of the telescopic rod 10 is rotatably connected to the short post 11.

[0033] Please see Figure 5 and Figure 7 A push plate 17 is fixedly installed on the push rod 19. Stabilizing columns 18 are provided on both sides of the push plate 17. The stabilizing columns 18 slide on the fixed frame 16. Pressing grooves 22 are provided on both sides of the push plate 17. Pressing blocks 23 are slidably connected in the pressing grooves 22. The pressing blocks 23 are connected to the push plate 17 by screws. A rubber strip 14 is placed in the pressing grooves 22. The middle part of the rubber strip 14 abuts against the pressing block 23. The two ends of the rubber strip 14 are fixedly installed to the movable ends of the telescopic rods 10 on both sides. A limit block 26 is fixedly installed on the sliding block 7. A counterweight rod 13 is rotatably connected between the limit blocks 26 on both sides. The counterweight rod 13 is made of metal iron and the cross section of the counterweight rod 13 is set in the shape of a teardrop.

[0034] Please see Figure 4 and Figure 5 The fixed frame 16 has a circular hole for the push rod 19 to slide. The central axis of the corresponding circular hole is in the same plane as the central axis of the threaded roller 2 and the lead screw 1. A second compression spring 20 is sleeved on the push rod 19. The two ends of the second compression spring 20 abut against the push plate 17 and the fixed frame 16 respectively.

[0035] Please see Figure 1 and Figure 2 The side wall of the circular block holder 5 has multiple evenly arranged grooves 29. The cross-section of the grooves 29 is rectangular, and the bottom of the grooves 29 is inclined upward. The inner wall of the outer shell 3 has a circular groove 4. The circular block holder 5 is rotatably connected in the circular groove 4. A rubber ring 8 is fixedly installed on the inner wall of the circular groove 4, and one side of the rubber ring 8 abuts against the circular block holder 5.

[0036] Please see Figure 6 and Figure 7 In actual use, the round block frame 5 is disassembled and then installed onto the threaded roller 2. Multiple locking frames 15 are inserted into the through holes 25 of the fan-shaped round plate 501, and the round block frame 5 is positioned in the annular groove 4. The pressing block 23 is opened, and the middle part of the rubber strip 14 is placed in the middle position of the pressing groove 22. The pressing block 23 is then placed over the rubber strip 14 and fixed with screws. At the same time, the two ends of the rubber strip 14 are fixed to the telescopic rods 10 on both sides.

[0037] Please see Figure 1 After installation, the planetary roller screw operates, and the screw 1 drives multiple threaded rollers 2 to rotate. Since it is a planetary structure, the multiple threaded rollers 2 will revolve around the central screw 1 while rotating. At the same time, the screw 1 has a helical structure, which allows the screw 1 to push the meshing threaded rollers 2 to move when rotating. When the screw 1 is running normally and slowly, it can smoothly drive the threaded rollers 2 and the outer shell 3 to move on the screw 1. However, when the screw 1 runs at high speed, the screw 1 needs to drive multiple threaded rollers 2 to revolve, which causes the threaded rollers 2 to generate centrifugal force. The centrifugal force causes the threaded rollers 2 to move towards the threaded grooves on the outer shell 3.

[0038] Please see Figure 2 , Figure 3 and Figure 4When the threaded roller 2 rotates, it drives the circular block frame 5 sleeved on the threaded roller 2 to rotate simultaneously. The high-speed rotation of the circular block frame 5 generates a corresponding centrifugal force according to the rotation speed. Therefore, the sliding block 7 sliding in the through groove 6 of the circular block frame 5 can move by the generated centrifugal force. At the same time, the movement of the sliding block 7 can squeeze the first compression spring 9 abutting on one side, causing the first compression spring 9 to contract. The movement of the sliding block 7 will drive the telescopic rod 10 rotatably connected to the sliding block 7 to move. The movable end of the telescopic rod 10 is rotatably connected to the circular block frame 5, so that the telescopic rod 10 forms a lever structure. The movable end of the telescopic rod 10 is connected to the push rod 19 through a connector. When the sliding block 7 moves to the outside of the circular block frame 5 due to centrifugal force, the movable end of the lower telescopic rod 10 will press against the rubber strip 14. The rubber strip 14 is stretched, which generates a certain tension and pushes the push plate 17 below to move. The telescopic rods 10 on both sides can compress the middle rubber strip 14, so that the push plate 17 moves with uniform force. It can be driven by the centrifugal force on both sides to generate the downward thrust of the rubber strip 14, avoiding excessive wear of the push rod 19 caused by long-term force on the same side. The push rod 19 pushes the ball 21 to abut against the threaded roller 2 below, preventing the threaded roller 2 from moving due to centrifugal force. Of course, the rubber strip 14 can also prevent the sliding block 7 from moving excessively, causing the telescopic rod 10 to compress the push plate 17 excessively. The push plate 17 is provided with stabilizing columns 18 on both sides to make the up and down movement of the push plate 17 more stable, and will not shake due to the round block frame 5 driving the push plate 17 to rotate for a long time.

[0039] Please see Figure 2 The circular block frame 5 rotates and scoops up the high-temperature lubricating oil below through the groove 29, spreading the lubricating oil onto the inner wall of the outer shell 3 for cooling. Of course, the bottom of the groove 29 is inclined upwards, which makes it easy for the groove 29 to scoop up the lubricating oil. The rubber ring 8 set on one side can seal the lubricating oil scooped out of the groove 29 to prevent the lubricating oil in the groove 29 from leaking due to centrifugal force.

[0040] Please see Figure 3 and Figure 7 By adding a counterweight rod 13, the centrifugal force generated by the sliding block 7 can be further increased. At the same time, the cross section of the counterweight rod 13 is teardrop-shaped. When it rotates at high speed around the lead screw 1, the teardrop head of the counterweight rod 13 will rotate outward, making the centrifugal force generated by the rotation of the counterweight rod 13 stronger. Of course, the counterweight rod 13 connects the sliding blocks 7 on both sides, allowing the sliding blocks 7 on both sides to move the same distance, so that the force applied by the telescopic rods 10 on both sides to the middle push rod 19 is the same, avoiding the push rod 19 from being subjected to greater force on one side than the other side, which would lead to increased wear.

[0041] Please see Figure 3 and Figure 6Of course, when the lead screw 1 resumes low-speed operation, the centrifugal force generated by the rotation of the circular block frame 5 cannot resist the squeezing force generated by the first compression spring 9. Therefore, the compressed first compression spring 9 will return to its original position and drive the sliding block 7 to return to its original position. Similarly, the telescopic rod 10 of the lever structure will return to its original position because the sliding block 7 returns to its original position, causing the compressed second compression spring 20 to return to its original position and drive the push rod 19 and the ball 21 away from the threaded roller 2.

[0042] The specific embodiment of the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the embodiments described above. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and ideas of the present invention should still fall within the protection scope of the present invention.

Claims

1. A planetary roller screw assembly, comprising a lead screw (1), a housing (3) sleeved on the lead screw (1), a plurality of threaded rollers (2) rotatably mounted inside the housing (3), one side of each threaded roller (2) being threadedly connected to the inner wall of the housing (3), and the other side of each threaded roller (2) being threadedly connected to the lead screw (1), characterized in that, The middle part of the threaded roller (2) is the optical axis. The housing (3) is provided with a fixing frame (16). The fixing frame (16) is located at the optical axis position of the threaded roller (2). A push rod (19) is slidably connected to the fixing frame (16). A ball (21) is slidably connected to one end of the push rod (19). A pushing assembly is provided inside the housing (3). The pushing assembly abuts against the push rod (19). When the threaded roller (2) rotates to the bottom or rotates rapidly, the pushing assembly pushes the threaded roller (2) to move through the push rod (19) and the ball (21) on the push rod (19), so that the threaded roller (2) moves closer to the central axis of the lead screw (1).

2. The planetary roller screw assembly according to claim 1, characterized in that, The pushing assembly includes a circular block frame (5), a limiting post (8), a sliding block (7), a first compression spring (9), a short post (11), a telescopic rod (10), and a rotating block (12). The circular block frame (5) is rotatably installed inside the outer shell (3). The circular block frame (5) is sleeved on the lead screw (1). The circular block frame (5) has multiple holes (27), and each threaded roller (2) passes through the corresponding hole (27). The circular block frame (5) has multiple through slots (6), and the limiting post (8) is fixedly installed in the through slot (6). The sliding block (7) is sleeved on the limiting post (8) and slidably connected in the through slot (6). A first compression spring (9) abuts against one side of the sliding block (7) and the inner wall of the through groove (6). The first compression spring (9) is sleeved on the limiting post (8). Two short posts (11) are fixedly installed on the sliding block (7). Multiple telescopic rods (10) are installed on the round block frame (5). A rotating block (12) is rotatably connected to the round block frame (5). The movable end of the telescopic rod (10) is fixedly installed with the rotating block (12). One end of the telescopic rod (10) is rotatably connected with the short post (11). The other end of the telescopic rod (10) is provided with a connector. The connector abuts against the push rod (19). The fixed frame (16) is fixedly installed in the middle of the two round block frames (5).

3. A planetary roller screw assembly according to claim 2, characterized in that, The connector includes a push plate (17), a stabilizing column (18), a pressing block (23), and a rubber strip (14). The push plate (17) is fixedly installed on the push rod (19). The push plate (17) has stabilizing columns (18) on both sides. The stabilizing columns (18) slide on the fixed frame (16). The push plate (17) has pressing grooves (22) on both sides. The pressing block (23) is slidably connected in the pressing groove (22). The pressing block (23) is connected to the push plate (17) by screws. The rubber strip (14) is placed in the pressing groove (22). The middle part of the rubber strip (14) abuts against the pressing block (23). The two ends of the rubber strip (14) are fixedly installed to the movable ends of the telescopic rods (10) on both sides.

4. A planetary roller screw assembly according to claim 3, characterized in that, The fixed frame (16) has a circular hole for sliding the push rod (19). The central axis of the circular hole is in the same plane as the central axis of the threaded roller (2) and the lead screw (1). A second compression spring (20) is sleeved on the push rod (19). The two ends of the second compression spring (20) abut against the push plate (17) and the fixed frame (16) respectively.

5. A planetary roller screw assembly according to claim 4, characterized in that, A limiting block (26) is fixedly installed on the sliding block (7), and a counterweight rod (13) is rotatably connected between the two limiting blocks (26). The counterweight rod (13) is made of metal iron, and the cross section of the counterweight rod (13) is teardrop-shaped.

6. A planetary roller screw assembly according to claim 2, characterized in that, The side wall of the circular block frame (5) is provided with a plurality of uniformly arranged grooves (29). The cross-section of the grooves (29) is rectangular, and the bottom of the grooves (29) is inclined upward.

7. A planetary roller screw assembly according to claim 6, characterized in that, The circular block frame (5) is evenly divided into four fan-shaped circular plates (501). Multiple through holes (25) are provided on both sides of the fan-shaped circular plates (501). Locking frames (15) are placed in the corresponding through holes (25) of two adjacent fan-shaped circular plates (501). Multiple rotating columns (24) are rotatably connected to the inner wall of the hole (27). When the threaded roller (2) passes through the hole (27), it abuts against the rotating column (24).

8. A planetary roller screw assembly according to claim 7, characterized in that, The inner wall of the outer shell (3) is provided with a circular groove (4), the circular block frame (5) is rotatably connected in the circular groove (4), and a rubber ring (8) is fixedly installed on the inner wall of the circular groove (4). One side of the rubber ring (8) abuts against the circular block frame (5).

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