Heavy-load planetary roller screw electric cylinder

Abstract

A heavy-load type planetary roller screw electric cylinder comprises an electric cylinder body, a planetary roller screw is arranged in the electric cylinder body and comprises an upper bearing, a lower bearing and a screw rod, the axis of the screw rod is vertically arranged, a circular boss is fixedly installed at the bottom end of the screw rod, the upper bearing and the lower bearing are sequentially arranged on the screw rod in a sleeving mode, and the upper bearing and the lower bearing are arranged on the screw rod in a sleeving mode. The upper bearing and the lower bearing are consistent in structure, the upper bearing and the lower bearing are oppositely arranged, the diameter of the upper bearing is gradually reduced from top to bottom, the upper bearing comprises an outer ring, an inner ring and a plurality of bearing rollers, the plurality of bearing rollers are arranged between the outer ring and the inner ring, the inner diameter of the outer ring is gradually reduced from top to bottom, and the inner diameter of the inner ring is gradually reduced from top to bottom. The outer diameter of the inner ring is gradually reduced from top to bottom, an annular groove is formed in the outer side of the inner ring, and a plurality of bearing rollers are axially arranged in the annular groove at equal intervals. Through the upper bearing, the lower bearing and the circular boss which are arranged in pairs, the radial loading force borne by the electric cylinder can be greatly improved, the heavy load capacity of the electric cylinder is improved, and the service life of the electric cylinder is prolonged.

Description

Technical Field

[0001] The utility model relates to the field of electric cylinders, in particular to a heavy-duty planetary roller screw electric cylinder. Background Art

[0002] Planetary roller screws rely on the rotation of the lead screw and rollers to drive the nut to make linear motion. The structure of the planetary roller screw is similar to that of the ball screw, including the lead screw, planetary rollers, cage, internal gear and nut, etc., in which the rolling elements are planetary rollers instead of the balls in the ball screw. The working principle of the planetary roller screw is similar to the mode of planets rotating around the sun in the solar system, in which the lead screw is equivalent to the sun, the planetary roller is equivalent to the planet, and the nut is equivalent to the orbit in the solar system. The active rotation of the lead screw drives the roller to revolve around the lead screw axis and rotate around its own axis, thereby driving the nut to make axial linear motion. The planetary roller screw generates linear contact rolling friction through meshing rollers, greatly increasing the contact surface and force surface of the screw transmission process. Compared with the ball screw used for precision transmission in the past, it has the characteristics of high speed, high load, high rigidity, high range lead, smaller size, lower noise, and easier maintenance and disassembly without much loss of transmission efficiency.

[0003] At present, the Chinese patent with the authorization announcement number CN111130263B discloses an integrated electric cylinder based on a reverse planetary roller screw, which belongs to the field of electric cylinder technology in aerospace, and solves the problem that the existing electric cylinder cannot achieve high-precision position closed-loop control, has no servo motor fault tolerance function, and needs to limit the rotation of the push rod by load. The integrated electric cylinder of the present invention is composed of a cylinder body, a bearing, a stator winding, a rotor permanent magnet, a nut sleeve, a roller screw, an encoder, an encoder mounting frame, an encoder mounting shaft and a magnetostrictive displacement sensor; the cylinder body includes a housing, an end cover and a guide sleeve, and the end cover and the guide sleeve are respectively arranged at both ends of the housing; the bearing sleeve is arranged in the housing, and the nut sleeve is arranged in the bearing; the nut sleeve is connected to the roller screw; the housing is connected to the stator winding, and the rotor permanent magnet is arranged on the outer surface of the nut sleeve. The present invention can achieve high-precision position closed-loop control, the stator windings are redundant with each other, and there is no need to increase the push rod to limit the rotation of the screw.

[0004] The above-mentioned existing technical solutions have the following defects: the reverse planetary roller screw is more suitable for work scenarios with small strokes and requiring an integrated design, but it wears more severely when faced with work scenarios with large transmission requirements and high loads, and it cannot withstand large radial loads relying solely on threaded connections. Utility Model Content

[0005] The utility model aims to provide a heavy-duty planetary roller screw electric cylinder to solve the problems existing in the above-mentioned prior art.

[0006] The above technical objectives of the utility model are achieved through the following technical solutions:

[0007] A heavy-duty planetary roller screw electric cylinder, comprising an electric cylinder body, a planetary roller screw disposed in the electric cylinder body, the planetary roller screw comprising an upper bearing, a lower bearing and a screw, the screw axis being arranged vertically, a circular boss being fixedly mounted at the bottom end of the screw, the upper bearing and the lower bearing being sleeved on the screw in sequence, the upper bearing and the lower bearing being both arranged at the bottom end of the circular boss, the upper bearing being arranged at the top of the lower bearing, the upper bearing being consistent with the lower bearing in structure, and the upper bearing being arranged opposite to the lower bearing;

[0008] The diameter of the upper bearing gradually decreases from top to bottom. The upper bearing includes an outer ring, an inner ring and bearing rollers. There are multiple bearing rollers, and the multiple bearing rollers are all arranged between the outer ring and the inner ring. The inner diameter of the outer ring gradually decreases from top to bottom, and the outer diameter of the inner ring gradually decreases from top to bottom. An annular groove is arranged on the outer side of the inner ring, and multiple bearing rollers are axially arranged at equal intervals in the annular groove.

[0009] By adopting the above technical solution, the circular boss at the bottom end of the screw is integrally formed with the screw, which will share the radial load force received by the electric cylinder during operation to the upper bearing and the lower bearing, and the upper bearing and the lower bearing are essentially a group of single-row tapered roller bearings arranged relatively to each other. The tapered roller bearings can limit the position of the screw and enhance the load-bearing capacity. As a better solution, a single-row cylindrical roller with a small taper angle is selected. The ability of a single-row tapered roller bearing to withstand axial loads depends on the contact angle, that is, the outer ring raceway angle. The radial load capacity of a small taper angle is large. When configured in pairs, it can be used to withstand pure radial loads, which greatly improves the heavy-load capacity of the electric cylinder.

[0010] In a further embodiment, the electric cylinder body includes a synchronous belt case, a servo motor, a cylinder body, a telescopic sleeve and an anti-rotation mechanism. The top of the synchronous belt case is provided with a first through hole and a second through hole at intervals. A mounting seat is bolted and fixed to the top of the first through hole, and the mounting seat is coaxially arranged with the first through hole. A telescopic hole is provided at the top of the cylinder body, and the cylinder body axis is vertically arranged at the top of the mounting seat. The telescopic hole is coaxially arranged with the first through hole. The telescopic sleeve 14 is rotatably installed on the top of the screw rod, and the telescopic hole is used to make the telescopic sleeve move up and down in the telescopic hole. An upper bearing and a lower bearing are fixedly installed in the mounting seat, and the screw rod is coaxially arranged with the first through hole. The anti-rotation mechanism is fixedly installed on the top of the mounting seat, and a mounting groove is provided on one side of the anti-rotation mechanism. A displacement sensor is fixedly installed in the mounting groove, and the servo motor and the planetary roller screw are spaced apart.

[0011] By adopting the above technical solution, the displacement sensor is used to monitor the speed and distance of the sleeve rising, so as to facilitate the linkage with the servo motor to control the movement accuracy of the electric cylinder, and the anti-rotation mechanism can prevent the sleeve from rotating during the rising process.

[0012] In a further embodiment, the servo motor is fixedly mounted on the top of the synchronous belt housing, the rotating shaft of the servo motor is arranged downward, and the rotating shaft of the servo motor is arranged coaxially with the second through hole.

[0013] By adopting the above technical solution, the rotating shaft of the servo motor and the bottom end of the planetary roller screw can be arranged in the synchronous belt housing, which can effectively prevent the transmission device from being affected by the outside world and causing accuracy problems.

[0014] In a further embodiment, a synchronous pulley is provided in the synchronous belt box, and the synchronous pulley includes a driving wheel, a driven wheel and a transmission belt. The driving wheel is sleeved on the bottom end of the rotating shaft of the servo motor, and the driven wheel is sleeved on the bottom end of the screw rod. The driving wheel and the driven wheel are connected by a transmission belt.

[0015] By adopting the above technical solution, the servo motor can drive the screw rod to rotate through the transmission device, and the rotation of the screw rod will drive the telescopic sleeve to move up and down.

[0016] In a further embodiment, a limit ring is provided at the bottom of the lower bearing, and the limit ring is used to limit the roller from sliding downward.

[0017] By adopting the above technical solution, when the electric cylinder is overloaded, the ball and the inner ring of the lower bearing may be offset in position, and the limit ring can prevent the roller position from changing.

[0018] In a further embodiment, a sealing gasket is provided on the telescopic hole.

[0019] By adopting the above technical solution, the sealing gasket on the telescopic hole can be dust-proof and oil-proof, thereby increasing the service life of the electric cylinder.

[0020] In summary, the utility model has the following beneficial effects:

[0021] 1. The upper and lower bearings are set up to promote the formation of lubricant film by relying on the excellent inner and outer ring design and roller finish, thereby reducing friction, which also reduces the heat generated by friction and the wear of the inner ring. In addition, the bearings can better maintain preload and reduce the noise level during operation. The inner and outer rings of the bearings are installed separately, and the separable parts are also interchangeable, which effectively prolongs the service life, improves operational reliability, and facilitates disassembly, assembly, maintenance and repair. The upper and lower bearings are single-row tapered roller bearings, which can adapt to radial loads and axial loads acting at the same time, and can withstand extremely heavy pure radial loads when configured in pairs, greatly improving the heavy-load capacity of the electric cylinder;

[0022] 2. Through the setting of the circular boss, the circular boss formed integrally with the screw rod can make the radial force borne by the telescopic sleeve on the screw rod not only rely on the threaded connection to disperse, but also disperse part of the force to the screw rod through the circular boss, and the bottom of the circular boss is in contact with the top of the upper bearing, and the upper and lower bearings configured in pairs can greatly withstand the radial force brought by the circular boss, which improves the operation capacity and heavy-load capacity of the electric cylinder, reduces the wear of the screw rod thread, and prolongs the service life of the screw rod;

[0023] 3. Through the setting of the limit ring, it can be set at the bottom of the lower bearing. When the electric cylinder is under heavy load and the telescopic sleeve transfers the force to the screw, the circular boss on the screw will transfer the force to the upper bearing and the lower bearing, preventing the inner ring and the bearing roller inside the lower bearing from sliding down, thereby improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the overall structure of a heavy-duty planetary roller screw electric cylinder of the utility model;

[0025] Figure 2 This is a structural schematic diagram of a planetary roller screw in a heavy-duty planetary roller screw electric cylinder of the utility model;

[0026] Figure 3 The utility model is a schematic diagram of the internal structure of a heavy-duty planetary roller screw electric cylinder for reflecting a transmission device.

[0027] In the figure, 1. electric cylinder body; 11. synchronous belt housing; 12. servo motor; 13. cylinder body; 14. telescopic sleeve; 15. anti-rotation mechanism; 16. mounting seat; 17. displacement sensor; 2. planetary roller screw; 21. upper bearing; 211. outer ring; 212. inner ring; 213. bearing roller; 22. lower bearing; 23. screw; 24. circular boss; 3. synchronous pulley; 31. driving wheel; 32. driven wheel; 33. transmission belt; 4. limit ring; 5. sealing gasket. DETAILED DESCRIPTION

[0028] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0029] The same parts are denoted by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the attached Figure 1 In the description of this specification, the words "bottom" and "top", "inside" and "outside" refer to directions toward or away from a particular component geometry, respectively. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this specification, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0030] Example:

[0031] like Figure 1-3 As shown, a heavy-duty planetary roller screw electric cylinder comprises an electric cylinder body 1, in which a planetary roller screw 2 is arranged, the planetary roller screw 2 comprises an upper bearing 21, a lower bearing 22 and a screw 23, the axis of the screw 23 is vertically arranged, a circular boss 24 is fixedly installed at the bottom end of the screw 23, the upper bearing 21 and the lower bearing 22 are sequentially sleeved on the screw 23, the upper bearing 21 and the lower bearing 22 are both arranged at the bottom end of the circular boss 24, the upper bearing 21 is arranged at the top of the lower bearing 22, the upper bearing 21 and the lower bearing 22 have the same structure, and the upper bearing 21 and the lower bearing 22 are arranged opposite to each other, a limit retaining ring 4 is arranged at the bottom of the lower bearing 22, the limit retaining ring 4 is used to limit the roller from sliding downward, the diameter of the upper bearing 21 gradually decreases from top to bottom, and the upper bearing 21 includes an outer ring 211, an inner ring 212 and bearing rollers 213. There are multiple bearing rollers 213, and the multiple bearing rollers 213 are all arranged between the outer ring 211 and the inner ring 212. The inner diameter of the outer ring 211 gradually decreases from top to bottom, and the outer diameter of the inner ring 212 gradually decreases from top to bottom. An annular groove is arranged on the outer side of the inner ring 212, and multiple bearing rollers 213 are axially arranged at equal intervals in the annular groove. Through the upper bearing 21 and the lower bearing 22 arranged in pairs up and down, the single-row tapered roller bearing with a small taper angle can effectively improve the radial bearing capacity, and the roller bearing can promote the formation of a lubricant film therein, thereby reducing friction and avoiding noise and vibration. The inner ring 212 and the outer ring 211 installed separately inside and outside are separable and interchangeable, which is conducive to disassembly, assembly, inspection and maintenance, so that the electric cylinder has excellent heavy-load capacity.

[0032] like Figure 1-3 As shown, the electric cylinder body 1 includes a synchronous belt case 11, a servo motor 12, a cylinder body 13, a telescopic sleeve 14 and an anti-rotation mechanism 15. The top of the synchronous belt case 11 is provided with a first through hole and a second through hole at intervals. A mounting seat 16 is bolted and fixed to the top of the first through hole. The mounting seat 16 is coaxially arranged with the first through hole. A telescopic hole is provided on the top of the cylinder body 13. A sealing gasket 5 is sleeved on the telescopic hole. The axis of the cylinder body 13 is vertically arranged on the top of the mounting seat 16. The telescopic hole is in contact with the mounting seat 16. The first through hole is coaxially arranged, the telescopic sleeve 14 is rotatably mounted on the top of the screw rod 23, the telescopic hole is used to make the telescopic sleeve 14 move up and down in the telescopic hole, the upper bearing 21 and the lower bearing 22 are fixedly installed in the mounting seat 16, the screw rod 23 is coaxially arranged with the first through hole, the anti-rotation mechanism 15 is fixedly installed on the top of the mounting seat 16, a mounting groove is arranged on one side of the anti-rotation mechanism 15, a displacement sensor 17 is fixedly installed in the mounting groove, the servo motor 12 and the planetary roller screw 2 are fixedly mounted. The servo motor 12 is fixedly mounted on the top of the synchronous belt case 11, the rotating shaft of the servo motor 12 is arranged downward, the rotating shaft of the servo motor 12 is arranged coaxially with the second through hole, and a synchronous pulley 3 is arranged in the synchronous belt case 11, the synchronous pulley 3 includes a driving wheel 31, a driven wheel 32 and a transmission belt 33, the driving wheel 31 is sleeved on the bottom end of the rotating shaft of the servo motor 12, the driven wheel 32 is sleeved on the bottom end of the screw rod 23, and the driving wheel 31 and the driven wheel 32 are connected by the transmission belt 33. Transmission connection, the servo motor 12 can improve the accuracy of the operation of the planetary roller screw 2, and the telescopic sleeve 14 will also be monitored by the displacement sensor 17 on the anti-rotation mechanism 15 on the side during the up and down movement, confirming the rising distance and rising speed of the telescopic sleeve 14, thereby cooperating with the servo motor 12 to increase or decrease the rotation speed of the screw 23, making this process smoother and more accurate, and the anti-rotation mechanism 15 can prevent the telescopic sleeve 14 from rotating during the up and down movement, thereby affecting the normal operation of the electric cylinder.

[0033] Specific implementation process: The upper bearing 21 and the lower bearing 22 are arranged at the bottom end of the screw rod 23. These two single-row tapered roller bearings arranged in pairs have a small taper angle, and the single-row tapered roller bearings arranged in pairs with a small taper angle can withstand pure radial loads and can be fixedly installed on the screw rod 23. The circular boss 24 arranged on the top of the upper bearing 21 makes the force of the telescopic sleeve 14 installed on the screw rod 23 no longer rely solely on the threaded connection to be transmitted to the bearing, but can disperse part of the radial load force through the circular boss 24, thereby slowing down the wear of the thread and improving the service life of the screw rod 23. At the same time, it also makes the electric cylinder more suitable for heavy-load scenarios. In addition, the anti-rotation mechanism 15 can prevent the telescopic sleeve 14 from rotating during the up and down movement, affecting the lifting accuracy and efficiency of the electric cylinder, and the displacement sensor 17 arranged in the groove on one side of the anti-rotation mechanism 15 is vertically arranged from bottom to top, which can accurately measure the telescopic sleeve The moving distance and moving speed of the cylinder 14 can improve the telescopic accuracy of the planetary roller electric cylinder. The telescopic sleeve 14 will be lifted or lowered from the telescopic hole at the top of the cylinder body 13. The periphery of the telescopic hole is provided with a sealing gasket 5 that can prevent dust and oil. The servo motor 12 serves as a driving device and can be adjusted in time according to the speed and distance sensed by the displacement sensor 17. When the lower bearing 22 is under heavy load, the limit ring 4 detachably installed at the bottom end of the lower bearing 22 plays an important role in limiting the inner ring 212 of the lower bearing 22 and the bearing roller 213. The bearing roller 213 itself is also truncated cone-shaped, and the truncated cone surface and the smaller surface of the bearing itself are kept consistent up and down. The bottom end of the rotating shaft of the driving device and the bottom end of the screw rod 23 of the planetary roller screw 2 are both provided with synchronous wheels. The driving wheel 31 and the driven wheel 32 are connected by a synchronous belt drive, and the bottom of the synchronous belt box 11 is also very smooth, which is convenient for installing the electric cylinder in a flat position.

[0034] In the embodiments disclosed in the present invention, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "connect" can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the embodiments disclosed in the present invention can be understood according to specific circumstances.

[0035] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A heavy-duty planetary roller screw (2) electric cylinder, comprising an electric cylinder body (1), wherein a planetary roller screw (2) is arranged in the electric cylinder body (1), characterized in that: The planetary roller screw (2) comprises an upper bearing (21), a lower bearing (22) and a screw (23); the axis of the screw (23) is vertically arranged; a circular boss (24) is fixedly mounted on the bottom end of the screw (23); the upper bearing (21) and the lower bearing (22) are sleeved on the screw (23) in sequence; the upper bearing (21) and the lower bearing (22) are both arranged at the bottom end of the circular boss (24); the upper bearing (21) is arranged on the top of the lower bearing (22); the upper bearing (21) and the lower bearing (22) have the same structure, and the upper bearing (21) and the lower bearing (22) are arranged opposite to each other; The diameter of the upper bearing (21) gradually decreases from top to bottom. The upper bearing (21) comprises an outer ring (211), an inner ring (212) and a bearing roller (213). A plurality of bearing rollers (213) are provided. The plurality of bearing rollers (213) are all provided between the outer ring (211) and the inner ring (212). The inner diameter of the outer ring (211) gradually decreases from top to bottom, and the outer diameter of the inner ring (212) gradually decreases from top to bottom. An annular groove is provided on the outer side of the inner ring (212), and a plurality of bearing rollers (213) are axially provided in the annular groove at equal intervals.

2. A heavy-duty planetary roller screw (2) electric cylinder according to claim 1, characterized in that: The electric cylinder body (1) comprises a synchronous belt case (11), a servo motor (12), a cylinder body (13), a telescopic sleeve (14) and an anti-rotation mechanism (15); a first through hole and a second through hole are arranged at intervals on the top of the synchronous belt case (11); a mounting seat (16) is bolted and fixed to the top of the first through hole; the mounting seat (16) is coaxially arranged with the first through hole; a telescopic hole is arranged on the top of the cylinder body (13); the axis of the cylinder body (13) is vertically arranged on the top of the mounting seat (16); the telescopic hole is coaxially arranged with the first through hole; The telescopic sleeve (14) is rotatably mounted on the top of the screw rod (23); the telescopic hole is used to enable the telescopic sleeve (14) to move up and down in the telescopic hole; an upper bearing (21) and a lower bearing (22) are fixedly mounted in the mounting seat (16); the screw rod (23) is coaxially arranged with the first through hole; the anti-rotation mechanism (15) is fixedly mounted on the top of the mounting seat (16); a mounting groove is arranged on one side of the anti-rotation mechanism (15); a displacement sensor (17) is fixedly mounted in the mounting groove; and the servo motor (12) and the planetary roller screw (2) are arranged at intervals.

3. A heavy-duty planetary roller screw (2) electric cylinder according to claim 2, characterized in that: The servo motor (12) is fixedly mounted on the top of the synchronous belt housing (11), the rotating shaft of the servo motor (12) is arranged downward, and the rotating shaft of the servo motor (12) is arranged coaxially with the second through hole.

4. A heavy-duty planetary roller screw (2) electric cylinder according to claim 2, characterized in that: A synchronous belt pulley (3) is arranged in the synchronous belt box (11), and the synchronous belt pulley (3) comprises a driving wheel (31), a driven wheel (32) and a transmission belt (33). The driving wheel (31) is sleeved on the bottom end of the rotating shaft of the servo motor (12), and the driven wheel (32) is sleeved on the bottom end of the screw rod (23). The driving wheel (31) and the driven wheel (32) are connected by transmission through the transmission belt (33).

5. A heavy-duty planetary roller screw (2) electric cylinder according to claim 3, characterized in that: A limit retaining ring (4) is provided at the bottom of the lower bearing (22), and the limit retaining ring (4) is used to limit the roller from sliding downward.

6. A heavy-duty planetary roller screw (2) electric cylinder according to claim 3, characterized in that: A sealing gasket (5) is sleeved on the telescopic hole.

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