阅读说明：本技术 一种多级并行式重载电动缸 (Multistage parallel type heavy-load electric cylinder ) 是由 申焱华 刘相新 张豪杰 谷捷 黎兰 于 2021-09-17 设计创作，主要内容包括：本发明提供一种多级并行式重载电动缸,属于电动缸技术领域。该电动缸包括行星滚柱丝杠轴、螺母、滚柱、缸筒、输入齿轮、伺服电机、减速齿轮、花键和传动筒。伺服电机与底座缸筒固定连接,伺服电机与减速齿轮相连,一级行星滚柱丝杠轴的一端与一级输入齿轮固定连接,另一端与花键A相连,一级螺母和滚柱围绕一级行星滚柱丝杠轴组成一体,二级行星滚柱丝杠轴一端与二级输入齿轮固定连接,另一端与花键B相连,二级螺母和滚柱围绕二级行星滚柱丝杠轴组成一体,三级行星滚柱丝杠轴与三级输入齿轮固定连接,三级螺母和滚柱围绕三级行星滚柱丝杠轴组成一体。本发明减小了空间体积,增强了承载能力,具有强抗弯和抗扭能力,提高了传动速度和传动效率。(The invention provides a multistage parallel heavy-load electric cylinder, and belongs to the technical field of electric cylinders. The electric cylinder comprises a planetary roller screw shaft, a nut, a roller, a cylinder barrel, an input gear, a servo motor, a reduction gear, a spline and a transmission barrel. Servo motor and base cylinder fixed connection, servo motor links to each other with reduction gear, the one end and the one-level input gear fixed connection of one-level planet roller screw shaft, the other end links to each other with spline A, one-level nut and roller are constituteed integratively around one-level planet roller screw shaft, second grade planet roller screw shaft one end and second grade input gear fixed connection, the other end links to each other with spline B, second grade nut and roller are constituteed integratively around second grade planet roller screw shaft, tertiary planet roller screw shaft and tertiary input gear fixed connection, tertiary nut and roller are constituteed integratively around tertiary planet roller screw shaft. The invention reduces the space volume, enhances the bearing capacity, has strong bending resistance and torsion resistance, and improves the transmission speed and the transmission efficiency.)

1. The utility model provides an electronic jar of multistage parallel mode heavy load which characterized in that: the device comprises a base cylinder barrel (1), a thrust cylindrical roller bearing (2), a primary input gear (3), a reduction gear (4), a motor output gear (5), a servo motor (6), a primary planet roller screw shaft (7), a primary nut (8), a roller A (9), a primary cylinder barrel (10), a transmission barrel A (11), a protective cover A (12), a secondary input gear (13), a secondary planet roller screw shaft (14), a secondary cylinder barrel (15), a secondary nut (16), a roller B (17), a transmission barrel B (18), a tertiary input gear (19), a protective cover B (20), a tertiary planet roller screw shaft (21), a tertiary nut (22), a roller C (23), a spline A (24), a tertiary cylinder barrel (25), an inner gear ring (26), a roller retainer (27) and a spline B (28); a servo motor (6) is fixedly connected with a base cylinder barrel (1), a servo motor shaft is connected with a motor output gear (5), one side of a reduction gear (4) is meshed with the motor output gear (5), the other side of the reduction gear is meshed with a primary input gear (3), one end of a primary planet roller screw shaft (7) is fixedly connected with the primary input gear (3), the other end of the primary planet roller screw shaft is fixedly connected with a spline A (24), a primary nut (8) and a roller A (9) form a whole by surrounding the primary planet roller screw shaft (7), the primary nut (8) is fixedly connected with a primary cylinder barrel (10), the spline A (24) is connected with the inside of a transmission barrel A (11), a gear on the outer side of the transmission barrel A (11) is meshed with a secondary input gear (13), one end of a secondary planet roller screw shaft (14) is fixedly connected with the secondary input gear (13), and the other end of the secondary planet roller screw shaft is connected with a spline B (28), a second-stage nut (16) and a roller B (17) are integrated around a second-stage planet roller screw shaft (14), the second-stage nut (16) is fixedly connected with a second-stage cylinder barrel (15), a spline B (28) is connected with the inside of a transmission barrel B (18), a gear on the outer side of the transmission barrel B (18) is meshed with a third-stage input gear (19), a third-stage planet roller screw shaft (21) is fixedly connected with the third-stage input gear (19), a third-stage nut (22) and a roller C (23) are integrated around the third-stage planet roller screw shaft (21), the third-stage nut (22) is fixedly connected with a third-stage cylinder barrel (25), and the outer sides of a roller A (9), the roller B (17) and the roller C (23) are respectively provided with an inner gear ring (26) and a roller retainer (27).

2. The multi-stage parallel heavy-duty electric cylinder according to claim 1, characterized in that: the lower parts of the first-stage input gear (3), the second-stage input gear (13) and the third-stage input gear (19) are all matched with a thrust cylindrical roller bearing (2).

3. The multi-stage parallel heavy-duty electric cylinder according to claim 1, characterized in that: the transmission cylinder A (11) and the secondary input gear (13) are fixedly connected with the primary cylinder barrel (10) through a protective cover A (12), and the protective cover A (12) limits the axial movement of the transmission cylinder A (11) and the secondary input gear (13); the transmission cylinder B (18) and the three-stage input gear (19) are fixedly connected with the second-stage cylinder barrel (15) through a protective cover B (20), and the protective cover B (20) limits the axial movement of the transmission cylinder B (18) and the three-stage input gear (19).

4. The multi-stage parallel heavy-duty electric cylinder according to claim 1, characterized in that: the first-stage cylinder barrel (10) has a symmetrical structure, and two first-stage planetary roller screw shafts (7), two first-stage nuts (8), two protective covers A (12), two transmission barrels A (11), two splines A (24) and two second-stage input gears (13) on the same-stage cylinder barrel form a parallel symmetrical structure; one-level input gear (3) drive one-level planet roller screw shaft (7) rotatory, two one-level planet roller screw shafts (7) rotate simultaneously, roller A (9) are revoluted around one-level planet roller screw shaft (7) simultaneously by the rotatory rotation that drives of one-level planet roller screw shaft (7), thereby drive two one-level nuts (8) axial and reciprocate, two one-level nuts (8) and one-level cylinder (10) fixed connection, axial reciprocating is realized in one-level cylinder (10).

5. The multi-stage parallel heavy-duty electric cylinder according to claim 1, characterized in that: the base cylinder barrel (1), the primary cylinder barrel (10), the secondary cylinder barrel (15) and the tertiary cylinder barrel (25) are provided with protruding structures on the inner side and the outer side of the cylinder barrel wall, so that the cylinder barrel is prevented from being separated; the base cylinder barrel (1) is provided with a positioning hole to limit the transverse swing of the motor output gear (5), the reduction gear (4) and the primary input gear (3), so that the stable power transmission is ensured; there is protruding structure in one-level cylinder (10) and second grade input gear (13) junction, and there is protruding structure in second grade cylinder (15) and tertiary input gear (19) junction, prevents the horizontal removal of second grade input gear (13) and tertiary input gear (19), guarantees that power transmission is steady.

6. The multi-stage parallel heavy-duty electric cylinder according to claim 1, characterized in that: the inner wall of the transmission cylinder A (11) is provided with a sliding groove which is meshed with the spline A (24), the inner wall of the transmission cylinder A (11) is provided with a convex structure, and when the spline A (24) axially slides to the convex structure, the movement is stopped, and the cylinder barrel is prevented from being separated.

7. The multi-stage parallel heavy-duty electric cylinder according to claim 1, characterized in that: and the three-stage cylinder barrel (25) is of a double-layer structure, so that the transmission cylinder A (11) and the transmission cylinder B (18) axially slide up and down, and the coaxiality is ensured.

8. The multi-stage parallel heavy-duty electric cylinder according to claim 1, characterized in that: when the electric cylinder is started, a servo motor (6) transmits power to a motor output gear (5), the motor output gear (5) transmits power to a reduction gear (4), the reduction gear (4) transmits power to a primary input gear (3), the primary input gear (3) drives a primary planet roller screw shaft (7) to rotate, the primary planet roller screw shaft (7), a primary nut (8), a roller A (9), an inner gear ring and a roller retainer form a screw pair, the roller A (9) is rotated by the primary planet roller screw shaft (7) to drive rotation and simultaneously revolve around the primary planet roller screw shaft (7), so that the primary nut (8) is driven to axially move up and down, the primary nut (8) is fixedly connected with a primary cylinder barrel (10), and the primary cylinder barrel (10) realizes axial up and down movement; the primary planet roller screw shaft (7) drives a spline A (24) to rotate, the spline A (24) drives a transmission cylinder A (11) to rotate and simultaneously axially move up and down along a sliding groove on the inner wall of the transmission cylinder A (11), a gear on the outer side of the transmission cylinder A (11) transmits power to a secondary input gear (13), the secondary input gear (13) drives a secondary planet roller screw shaft (14) to rotate, the secondary planet roller screw shaft (14), a secondary nut (16), a roller B (17), an inner gear ring and a roller retainer form a screw pair, the roller B (17) is driven by the rotation of the secondary planet roller screw shaft (14) to rotate and simultaneously revolve around the secondary planet roller screw shaft (14), thereby driving the second-stage nut (16) to move up and down axially, the second-stage nut (16) is fixedly connected with the second-stage cylinder barrel (15), and the second-stage cylinder barrel (15) realizes the up and down movement axially; the second-stage planet roller screw shaft (14) drives a spline B (28) to rotate, the spline B (28) drives the transmission cylinder B (18) to rotate and simultaneously axially move up and down along a chute on the inner wall of the transmission cylinder B (18), a gear on the outer side of the transmission cylinder B (18) transmits power to a third-stage input gear (19), the third-stage input gear (19) drives a third-stage planet roller screw shaft (21) to rotate, the third-stage planet roller screw shaft (21), a third-stage nut (22), a roller C (23), an inner gear ring and a roller retainer form a screw pair, the roller C (23) is driven by the third-stage planet roller screw shaft (21) to rotate and revolve around the third-stage planet roller screw shaft (21), thereby drive tertiary nut (22) axial and reciprocate, tertiary nut (22) and tertiary cylinder (25) fixed connection, tertiary cylinder (25) realize the axial and reciprocate.

Technical Field

The invention relates to the technical field of electric cylinders, in particular to a multistage parallel type heavy-load electric cylinder.

Background

The electric cylinder is a product which integrates a servo motor and a lead screw, the rotary motion of the motor is converted into the linear motion of a push rod through the mechanical motion of the lead screw and a lead screw pair, the reciprocating motion of an output shaft is realized through the positive and negative rotation of the motor, and the remote control and the centralized control can be realized; the device has the performance characteristics of high transmission efficiency, high positioning accuracy, high reliability and safety, high response speed, high control accuracy and high synchronism.

The existing servo electric cylinder has a complex overall structure and a large overall volume, occupies a large space in applied mechanical equipment, is inconvenient to install and has a small application range; meanwhile, the cable is easy to wear, short in service life, high in noise and inconvenient to connect with external parts; in some occasions with small volume, high precision requirement and large load, the existing product can not meet the use requirement. In order to obtain a more practical and effective use function of the electric cylinder for a special working occasion, the performance of the electric cylinder needs to be improved.

The electric cylinder is used as a core execution mechanism of equipment such as a fully electric combat vehicle, a multi-degree-of-freedom robot and the like, and is widely applied to the fields of vehicle-mounted leveling and erecting, astronomical instrument observation and the like. Because of the reasons of small expansion ratio, large volume, small bearing capacity and the like of a common electric cylinder, at present, a multi-stage hydraulic cylinder is still adopted in the fields of vertical launching and the like which require small installation space and long working stroke. In the working process of the multi-stage hydraulic cylinder, the problems of large stage-changing impact, phenomena of 'running, overflowing, dripping and leaking' and the like exist, and large-scale vertical launching is always troubled. Therefore, the research on the multi-stage electric cylinder with large expansion ratio, small volume and large load capacity becomes one of the key technologies for the research on the fully-electric vehicles.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a multistage parallel type heavy-load electric cylinder, which realizes that the multistage electric cylinder has smaller axial size and can provide larger working stroke, adopts a parallel type structure, realizes the flattening of the electric cylinder, reduces the space volume, strengthens the load capacity of the electric cylinder, increases the bending resistance and torsion resistance, and has good expansibility and modularization; and a synchronous transmission structure is adopted, so that the primary cylinder barrel, the secondary cylinder barrel and the tertiary cylinder barrel realize synchronous axial movement, and the transmission speed and the transmission efficiency are improved.

The electric cylinder comprises a base cylinder barrel, a thrust cylindrical roller bearing, a primary input gear, a reduction gear, a motor output gear, a servo motor, a primary planet roller screw shaft, a primary nut, a roller A, a primary cylinder barrel, a transmission barrel A, a protective cover A, a secondary input gear, a secondary planet roller screw shaft, a secondary cylinder barrel, a secondary nut, a roller B, a transmission barrel B, a tertiary input gear, a protective cover B, a tertiary planet roller screw shaft, a tertiary nut, a roller C, a spline A, a tertiary cylinder barrel, an inner gear ring, a roller retainer and a spline B; a servo motor is fixedly connected with a base cylinder, a servo motor shaft is connected with a motor output gear, one side of a reduction gear is meshed with the motor output gear, the other side of the reduction gear is meshed with a primary input gear, one end of a primary planet roller screw shaft is fixedly connected with the primary input gear, the other end of the primary planet roller screw shaft is fixedly connected with a spline A, the primary nut and the roller A are integrated around the primary planet roller screw shaft, the primary nut is fixedly connected with the primary cylinder, the spline A is connected with a transmission cylinder A, an outer side gear of the transmission cylinder A is meshed with a secondary input gear, one end of the secondary planet roller screw shaft is fixedly connected with the secondary input gear, the other end of the secondary planet roller screw shaft is connected with a spline B, the secondary nut and the roller B are integrated around the secondary planet roller screw shaft, the secondary nut is fixedly connected with the secondary cylinder, the spline B is connected with the transmission cylinder B, the outer side gear of the transmission cylinder B is meshed with a tertiary input gear, the three-stage planetary roller screw shaft is fixedly connected with the three-stage input gear, the three-stage nut and the roller C form a whole around the three-stage planetary roller screw shaft, the three-stage nut is fixedly connected with the three-stage cylinder barrel, and the outer sides of the roller A, the roller B and the roller C are all provided with an inner gear ring and a roller retainer.

Wherein, the lower parts of the first-stage input gear, the second-stage input gear and the third-stage input gear are all matched with a thrust cylindrical roller bearing.

The transmission cylinder A and the secondary input gear are fixedly connected with the primary cylinder barrel through a protective cover A, and the protective cover A limits the axial movement of the transmission cylinder A and the secondary input gear; and the transmission cylinder B and the three-level input gear are fixedly connected with the second-level cylinder barrel through a protective cover B, and the protective cover B limits the axial movement of the transmission cylinder B and the three-level input gear.

The first-stage cylinder barrel has a symmetrical structure, and two first-stage planetary roller screw shafts, two first-stage nuts, two protective covers A, two transmission barrels A, two splines A and two second-stage input gears on the same-stage cylinder barrel form a parallel symmetrical structure; the one-level input gear drives the one-level planet roller screw shaft to rotate, the two one-level planet roller screw shafts rotate simultaneously, the roller A is driven to rotate by the rotation of the one-level planet roller screw shaft and revolve around the one-level planet roller screw shaft simultaneously, so that the two one-level nuts are driven to axially move up and down, the two one-level nuts are fixedly connected with the one-level cylinder barrel, and the one-level cylinder barrel realizes the axial up and down movement.

The base cylinder barrel, the primary cylinder barrel, the secondary cylinder barrel and the tertiary cylinder barrel are provided with protruding structures on the inner side and the outer side of the cylinder barrel wall, so that the cylinder barrel is prevented from being separated; the base cylinder barrel is provided with a positioning hole to limit the transverse swing of the motor output gear, the reduction gear and the primary input gear, so that the stable power transmission is ensured; there is the protrusion structure in one-level cylinder and second grade input gear junction, and there is the protrusion structure in second grade cylinder and tertiary input gear junction, prevents the horizontal removal of second grade input gear and tertiary input gear, guarantees that power transmission is steady.

The inner wall of the transmission cylinder A is provided with a sliding groove which is meshed with the spline A, the inner wall of the transmission cylinder A is provided with a convex structure, and when the spline A slides to the convex structure in the axial direction, the cylinder barrel is prevented from being separated by stopping movement.

The third-stage cylinder barrel is of a double-layer structure, so that the transmission cylinder A and the transmission cylinder B axially slide up and down, and the coaxiality is guaranteed.

When the electric cylinder is started, a servo motor transmits power to a motor output gear, the motor output gear transmits power to a reduction gear, the reduction gear transmits power to a primary input gear, the primary input gear drives a primary planetary roller screw shaft to rotate, the primary planetary roller screw shaft, a primary nut, a roller A, an inner gear ring and a roller retainer form a screw pair, the roller A is driven by the rotation of the primary planetary roller screw shaft to rotate and simultaneously revolve around the primary planetary roller screw shaft, so that the primary nut is driven to axially move up and down, the primary nut is fixedly connected with a primary cylinder barrel, and the primary cylinder barrel realizes axial up and down movement; the first-stage planetary roller screw shaft drives the spline A to rotate, the spline A drives the transmission cylinder A to rotate and simultaneously axially move up and down along a sliding groove in the inner wall of the transmission cylinder A, a gear on the outer side of the transmission cylinder A transfers power to the second-stage input gear, the second-stage input gear drives the second-stage planetary roller screw shaft to rotate, the second-stage planetary roller screw shaft, the second-stage nut, the roller B, the inner gear ring and the roller holder form a screw pair, the roller B is driven by the rotation of the second-stage planetary roller screw shaft to rotate and simultaneously revolve around the second-stage planetary roller screw shaft, so that the second-stage nut is driven to axially move up and down, the second-stage nut is fixedly connected with the second-stage cylinder barrel, and the second-stage cylinder barrel realizes axial up and down movement; the second-level planetary roller screw shaft drives the spline B to rotate, the spline B drives the transmission cylinder B to rotate and simultaneously axially move up and down along a sliding groove in the inner wall of the transmission cylinder B, a gear on the outer side of the transmission cylinder B transmits power to the third-level input gear, the third-level input gear drives the third-level planetary roller screw shaft to rotate, the third-level planetary roller screw shaft and the third-level nut, a roller C, an inner gear ring and a roller retainer form a screw pair, the roller C is driven to rotate by the rotation of the third-level planetary roller screw shaft and simultaneously revolves around the third-level planetary roller screw shaft, so that the third-level nut is driven to axially move up and down, the third-level nut is fixedly connected with the third-level cylinder barrel, and the third-level cylinder barrel realizes axial movement up and down.

The technical scheme of the invention has the following beneficial effects:

in the scheme, a novel multistage parallel type screw transmission mechanism is designed according to a special mechanism combination theory through the characteristics of small size, large bearing capacity and high precision and high efficiency of the planetary roller screw. The same-stage cylinder barrel adopts a parallel double-planet roller screw structure, so that the volume of the electric cylinder is obviously reduced, the electric cylinder has a flat characteristic, the synchronous lifting of the two planet roller screws is realized, and the bearing capacity and the axial rigidity of the electric cylinder are improved. The power transmission between the planetary roller screws adopts the design of the transmission cylinders, so that the intermediate transmission links are reduced, the transmission of torque is realized without influencing sliding, the synchronous axial movement of a plurality of cylinders is realized, and the transmission efficiency and the transmission speed are improved.

The projection of each cylinder barrel and the projection of the inner wall of the transmission barrel limit the stroke of the planetary roller screw, effectively prevent each cylinder barrel from being separated and ensure the stability of the structure. The third-stage cylinder barrel adopts a double-layer design, so that the coaxiality of the transmission barrel is ensured while the transmission barrel slides up and down in the axial direction, and the bending resistance and the torsion resistance of the electric cylinder are increased. The parallel structure of the two planetary roller screw rods can realize expansion, more planetary roller screw rods can be connected in parallel in the same stage of cylinder barrel according to the transmission principle of the transmission barrel, and the load capacity of the electric cylinder is improved. The transmission principle of the transmission cylinder can be adopted, the structure with more levels is realized on the basis of the three-level electric cylinder, and the lifting height of the electric cylinder is improved. The transmission principle of the transmission cylinder can be adopted, three planetary roller screws are connected in parallel to form a ring, the same-stage cylinder is lifted, and larger load capacity is realized. The second-stage planet roller screw shaft or the third-stage planet roller screw shaft can be replaced by a series-type second-stage electric cylinder structure, so that series-parallel connection combination of electric cylinders is realized, and a new structure is formed to reduce the length of the electric cylinders.

Drawings

FIG. 1 is a schematic diagram of a multi-stage parallel heavy-duty electric cylinder according to the present invention;

FIG. 2 is a schematic diagram of the internal structure of a multi-stage parallel heavy-duty electric cylinder according to the present invention;

fig. 3 is a top view of a transmission cylinder of the multi-stage parallel heavy-duty electric cylinder of the present invention.

Wherein: 1-a base cylinder; 2-a thrust cylindrical roller bearing; 3-a primary input gear; 4-a reduction gear; 5-motor output gear; 6-a servo motor; 7-a first-stage planet roller screw shaft; 8-first-stage nut; 9-roller A; 10-first-stage cylinder barrel; 11-transmission cylinder A; 12-protective cover a; 13-a secondary input gear; 14-a secondary planet roller screw shaft; 15-a secondary cylinder barrel; 16-a secondary nut; 17-roller B; 18-transmission cylinder B; 19-a tertiary input gear; 20-protective cover B; 21-three-stage planet roller screw shaft; 22-a tertiary nut; 23-roller C; 24-spline a; 25-a three-stage cylinder barrel; 26-inner gear ring; 27-a roller cage; 28-spline B.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

The invention provides a multistage parallel heavy-load electric cylinder.

As shown in fig. 1, 2 and 3, the electric cylinder includes a base cylinder 1, a thrust cylindrical roller bearing 2, a primary input gear 3, a reduction gear 4, a motor output gear 5, a servo motor 6, a primary planetary roller screw shaft 7, a primary nut 8, a roller a9, a primary cylinder 10, a transmission cylinder a11, a protective cover a12, a secondary input gear 13, a secondary planetary roller screw shaft 14, a secondary cylinder 15, a secondary nut 16, a roller B17, a transmission cylinder B18, a tertiary input gear 19, a protective cover B20, a tertiary planetary roller screw shaft 21, a tertiary nut 22, a roller C23, a spline a24, a tertiary cylinder 25, an inner ring gear 26, a roller holder 27 and a spline B28; the servo motor 6 is fixedly connected with the base cylinder barrel 1, a servo motor shaft is connected with a motor output gear 5, one side of a reduction gear 4 is meshed with the motor output gear 5, the other side of the reduction gear is meshed with a primary input gear 3, one end of a primary planet roller screw shaft 7 is fixedly connected with the primary input gear 3, the other end of the primary planet roller screw shaft is fixedly connected with a spline A24, a primary nut 8 and a roller A9 are integrated around the primary planet roller screw shaft 7, the primary nut 8 is fixedly connected with a primary cylinder barrel 10, a spline A24 is connected with a transmission barrel A11, a gear outside the transmission barrel A11 is meshed with a secondary input gear 13, one end of a secondary planet roller screw shaft 14 is fixedly connected with the secondary input gear 13, the other end of the secondary planet roller screw shaft is connected with a spline B28, a secondary nut 16 and a roller B17 are integrated around the secondary planet roller screw shaft 14, the secondary nut 16 is fixedly connected with a secondary cylinder barrel 15, the spline B28 is connected with the transmission barrel B18, an outer side gear of the transmission cylinder B18 is meshed with the third-stage input gear 19, the third-stage planetary roller screw shaft 21 is fixedly connected with the third-stage input gear 19, the third-stage nut 22 and the roller C23 are integrated around the third-stage planetary roller screw shaft 21, the third-stage nut 22 is fixedly connected with the third-stage cylinder barrel 25, and inner gear rings 26 and a roller retainer 27 are arranged on the outer sides of the roller A9, the roller B17 and the roller C23.

In actual design, the lower parts of the primary input gear 3, the secondary input gear 13 and the tertiary input gear 19 are all matched with the thrust cylindrical roller bearing 2.

The transmission cylinder A11 and the secondary input gear 13 are fixedly connected with the primary cylinder 10 through a protective cover A12, and the protective cover A12 limits the axial movement of the transmission cylinder A11 and the secondary input gear 13; the transmission cylinder B18 and the tertiary input gear 19 are fixedly connected with the secondary cylinder 15 through a protective cover B20, and the protective cover B20 limits the axial movement of the transmission cylinder B18 and the tertiary input gear 19.

A symmetrical structure is arranged on the first-stage cylinder barrel 10, and two first-stage planet roller screw shafts 7, two first-stage nuts 8, two protective covers A12, two transmission barrels A11, two splines A24 and two second-stage input gears 13 which form a parallel symmetrical structure are arranged on the same-stage cylinder barrel; the one-level input gear 3 drives the one-level planet roller screw shaft 7 to rotate, the two one-level planet roller screw shafts 7 rotate simultaneously, the roller A9 is driven by the rotation of the one-level planet roller screw shaft 7 to rotate and simultaneously revolve around the one-level planet roller screw shaft 7, so that the two one-level nuts 8 are driven to axially move up and down, the two one-level nuts 8 are fixedly connected with the one-level cylinder barrel 10, and the one-level cylinder barrel 10 realizes the axial up-and-down movement.

The base cylinder barrel 1, the first-stage cylinder barrel 10, the second-stage cylinder barrel 15 and the third-stage cylinder barrel 25 are provided with protruding structures on the inner side and the outer side of the cylinder barrel wall, so that the cylinder barrels are prevented from being separated; the base cylinder barrel 1 is provided with a positioning hole to limit the transverse swing of the motor output gear 5, the reduction gear 4 and the primary input gear 3, so that the stable power transmission is ensured; there is protruding structure in one-level cylinder 10 and second grade input gear 13 junction, and there is protruding structure in second grade cylinder 15 and tertiary input gear 19 junction, prevents the horizontal removal of second grade input gear 13 and tertiary input gear 19, guarantees that power transmission is steady.

The inner wall of the transmission cylinder A11 is provided with a sliding groove which is meshed with the spline A24, and meanwhile, the inner wall of the transmission cylinder A11 is provided with a protruding structure, when the spline A24 axially slides to the protruding structure, the movement is stopped, and the cylinder barrel is prevented from being separated.

The third-stage cylinder 25 is of a double-layer structure, so that the transmission cylinder A11 and the transmission cylinder B18 axially slide up and down, the coaxiality is ensured, and the bending resistance and torsion resistance of the electric cylinder are enhanced.

The two first-stage input gears, the two reduction gears, the motor output gear, the two transmission cylinders A, the two second-stage input gears, the two transmission cylinders B and the two third-stage input gears are axially supported by the thrust cylindrical roller bearing.

In a specific application, when the electric cylinder is started, the servo motor 6 transmits power to the motor output gear 5, the motor output gear 5 transmits power to the reduction gear 4, the reduction gear 4 transmits power to the primary input gear 3, the primary input gear 3 drives the primary planet roller screw shaft 7 to rotate, the primary planet roller screw shaft 7, the primary nut 8, the roller A9, the inner gear ring and the roller retainer form a screw pair, the roller A9 is driven by the rotation of the primary planet roller screw shaft 7 to rotate and revolve around the primary planet roller screw shaft 7 at the same time, so that the primary nut 8 is driven to move up and down axially, the primary nut 8 is fixedly connected with the primary cylinder barrel 10, and the primary cylinder barrel 10 realizes the axial up and down movement; the primary planet roller screw shaft 7 drives a spline A24 to rotate, the spline A24 drives a transmission cylinder A11 to rotate and simultaneously axially move up and down along a sliding groove on the inner wall of the transmission cylinder A11, a gear on the outer side of the transmission cylinder A11 transmits power to a secondary input gear 13, the secondary input gear 13 drives a secondary planet roller screw shaft 14 to rotate, the secondary planet roller screw shaft 14, a secondary nut 16, a roller B17, an inner gear ring and a roller retainer form a screw pair, a roller B17 is driven to rotate by the rotation of the secondary planet roller screw shaft 14 and simultaneously revolves around the secondary planet roller screw shaft 14, so that the secondary nut 16 is driven to axially move up and down, the secondary nut 16 is fixedly connected with a secondary cylinder 15, and the secondary cylinder 15 axially moves up and down; the second-stage planetary roller screw shaft 14 drives a spline B28 to rotate, the spline B28 drives a transmission cylinder B18 to rotate and simultaneously axially move up and down along a sliding groove in the inner wall of the transmission cylinder B18, a gear on the outer side of the transmission cylinder B18 transmits power to a third-stage input gear 19, the third-stage input gear 19 drives a third-stage planetary roller screw shaft 21 to rotate, the third-stage planetary roller screw shaft 21, a third-stage nut 22, a roller C23, an inner gear ring and a roller retainer form a screw pair, the roller C23 is driven to rotate and revolve around the third-stage planetary roller screw shaft 21 by the rotation of the third-stage planetary roller screw shaft 21, so that the third-stage nut 22 is driven to axially move up and down, the third-stage nut 22 is fixedly connected with the third-stage cylinder 25, and the third-stage cylinder 25 axially moves up and down; the three cylinders realize synchronous axial movement, and the transmission speed and the transmission efficiency are improved.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.