Two-stage planetary gear speed reducer and transmission structure thereof

Abstract

The invention relates to the technical field of speed reducers, in particular to a two-stage planetary gear speed reducer and a transmission structure thereof.The two-stage planetary gear speed reducer comprises a first-stage sun gear, an inner gear ring, a first-stage planetary set, a first-stage planetary carrier, a second-stage sun gear, a second-stage planetary set and a second-stage planetary carrier, the first-stage sun gear serves as a first-stage input end, and the second-stage sun gear serves as a second-stage input end; the first-stage sun gear and the second-stage sun gear can both adjust the axial position in a floating mode, the first-stage planet carrier comprises a bottom frame, a top frame and an adjusting frame, the bottom frame, the top frame and the adjusting frame rotate synchronously, a positioning ring is fixedly connected to the inner ring of the inner gear ring and located between the top frame and the bottom frame, and the positioning ring is located between the top frame and the bottom frame. According to the planet carrier, the problem that the connecting line of the center of a planet wheel and the center of a sun wheel is not strictly horizontal after the planet wheel shifts downwards is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of reducers, and in particular to a double-stage planetary gear reducer and a transmission structure thereof. Background Art

[0002] Planetary reducer is a widely used industrial product that can reduce the speed of the motor and increase the output torque. As a power transmission device connecting the power source and the actuator, it is indispensable in the field of transmission equipment in industries such as lifting, excavation, transportation, construction, metallurgy, and industrial production.

[0003] The transmission structure of a traditional two-stage planetary gear reducer includes a primary input stage and a secondary output stage planetary gear set, and adopts a coaxial and unidirectional transmission design. In a vertically installed two-stage planetary gear reducer, the reducer axis is perpendicular to the ground, and the gravity direction of the planetary gear is consistent with the axis direction. Each planetary gear will be continuously affected by its own gravity, causing it to produce a downward static eccentric load on the planetary carrier pin shaft. The planetary gear is installed on the planetary carrier pin shaft through a bearing. Gravity will cause the center of the planetary gear to move slightly downward. After the planetary gear is offset downward, the line connecting its center and the center of the sun gear is no longer strictly horizontal, resulting in differences in the meshing angles of each planetary gear and the sun gear, and uneven load distribution. Summary of the invention

[0004] The object of the present invention is to provide a two-stage planetary gear reducer and a transmission structure thereof, so as to solve the problem that after the planetary gear deviates downward, the line connecting the center of the planetary gear and the center of the sun gear is no longer strictly horizontal.

[0005] To achieve the above object, the present invention provides the following technical solutions: A double-stage planetary gear transmission structure comprises a primary sun gear, an inner gear ring, a primary planet set, a primary planet carrier, a secondary sun gear, a secondary planet set, and a secondary planet carrier. The primary sun gear serves as a primary input end, and the secondary sun gear serves as a secondary input end. Both the primary sun gear and the secondary sun gear can float and adjust their axial positions.

[0006] Preferably, the first-stage planetary frame includes a bottom frame, a top frame and an adjusting frame, and the bottom frame, the top frame and the adjusting frame rotate synchronously.

[0007] Preferably, the inner ring of the inner gear ring is fixedly connected with a positioning ring, and the positioning ring is located between the top frame and the bottom frame.

[0008] Preferably, the surfaces of the base frame and the secondary planetary frame are both provided with a plurality of evenly distributed pins, and each of the pins is provided with an axially adjustable component.

[0009] Preferably, the first-stage planetary gear set includes a plurality of first planet gears evenly distributed, and the second-stage planetary gear set includes a plurality of second planet gears evenly distributed. Both the first planet gears and the second planet gears are connected to the pin shaft through axially adjustable components.

[0010] Preferably, force sensors are installed on both the first-stage planet carrier and the second-stage planet carrier, and the force sensors are used to monitor the loads of the planet gears.

[0011] Preferably, ball bearings are provided on the contact surfaces of the positioning ring with the bottom frame and the top frame.

[0012] A two-stage planetary gear reducer includes the transmission structure and the housing, and the internal gear ring is fixedly connected to the inner wall of the housing.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The first-stage sun gear and the second-stage sun gear adopt a floating structure, which can adjust the axial position, compensate for the axial offset of the planet gears in real time, ensure good meshing between the gears, adjust the load distribution, avoid overloading of the planet gears, significantly improve the transmission smoothness, and reduce vibration and noise; 2. The planet gears are axially adjusted through axially adjustable components, and in cooperation with crowned teeth or modified teeth, the edge contact stress is reduced, the meshing angle change caused by slight axial offset is adapted, the power loss is reduced, and the transmission efficiency is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a cross-sectional view of the overall structure of the present invention; Figure 2 is a schematic structural view of the first-stage planet carrier of the present invention; Figure 3 is a schematic structural view of the planet gear of the present invention; Figure 4 is a vertical cross-sectional structural view of the axially adjustable component of the present invention.

[0015] In the figure: 1, housing; 2, first-stage sun gear; 3, hollow shaft; 4, bottom frame; 5, internal gear ring; 6, second-stage sun gear; 7, second planet gear; 8, second-stage planet carrier; 9, fixed pin; 10, positioning ring; 11, linear guide post; 12, top frame; 13, adjusting frame; 14, pin shaft. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0017] Please refer to Figure 1 , the present invention provides a technical solution.

[0018] A two-stage planetary gear transmission structure includes a first-stage sun gear 2, an internal gear ring 5, a first-stage planetary gear set, a first-stage planetary carrier, a second-stage sun gear 6, a second-stage planetary gear set, and a second-stage planetary carrier 8. The first-stage sun gear 2 is rigidly connected to the motor input shaft through a flat key and serves as the first-stage power input end. The second-stage sun gear 6 serves as the second-stage input end. The first-stage planetary carrier is connected to the second-stage sun gear 6, and the second-stage planetary carrier 8 outputs. The transmission direction of the transmission structure is coaxial and in the same direction for input and output. Both the first-stage sun gear 2 and the second-stage sun gear 6 adopt a floating design, which can balance the loads of each planetary gear and improve the transmission smoothness. The first-stage planetary gear set includes three or four evenly distributed first planetary gears, which are installed on the pin shafts 14 of the first-stage planetary carrier through an axially adjustable component and can rotate freely around their own axes. The first planetary gears are simultaneously meshed with the external teeth of the first-stage sun gear 2 and the internal teeth of the internal gear ring 5 to form a planetary transmission pair; The first-stage planetary carrier serves as the output end of the first stage and is coaxially connected to the external spline of the second-stage sun gear 6 through a spline to transmit power to the second-stage transmission; The second-stage sun gear 6 is connected to the first-stage planetary carrier. The second-stage planetary gear set includes three or four evenly distributed second planetary gears 7, which are installed on the pin shafts 14 of the second-stage planetary carrier through an axially adjustable component. The structural form is the same as that of the first planetary gears. The second planetary gears 7 are simultaneously meshed with the external teeth of the second-stage sun gear 6 and the internal teeth of the internal gear ring 5 to form a second-stage planetary transmission pair. The second-stage planetary carrier 8 serves as the output end of the system and is rigidly connected to the load through a flange to transmit torque to the external actuator.

[0019] The first-stage planetary carrier includes a bottom frame 4, a top frame 12, and an adjusting frame 13. The bottom frame 4, the top frame 12, and the adjusting frame 13 rotate synchronously. The bottom frame 4 and the top frame 12 are firmly connected by a fixing pin 9 to form the basic framework of the first-stage planetary carrier. The adjusting frame 13 is floatingly connected to the top frame 12. The adjusting frame 13 is coaxially connected to the second-stage sun gear 6. The adjusting frame 13 can float flexibly, thereby driving the second-stage sun gear 6 to adjust the axial position and realizing the adaptive adjustment of the axial offset of the planetary gears.

[0020] The bottom frame 4, as the basic supporting component of the first-stage planetary carrier, is made of high-strength alloy steel to withstand the large loads generated during the operation of the speed reducer. Its shape is circular and has pin shafts 14 for installing the first planetary gears. A number of through holes matching the fixing pins 9 are evenly distributed on the edge of the bottom frame 4 for connecting to the top frame 12. The second-stage planetary carrier 8 also has pin shafts 14 for installing the second planetary gears 7, and the installation method of the second planetary gears 7 is the same as that of the first planetary gears.

[0021] The top frame 12 is located above the bottom frame 4 and is also made of high-strength alloy steel. Its shape corresponds to that of the bottom frame 4 and is a circular structure. A central through-hole is provided at the center position of the adjusting frame 13 for accommodating the top frame 12. On the upper surface of the top frame 12, linear guide posts 11 are arranged around the central through-hole. Corresponding threaded holes are provided at the positions of the top frame 12 corresponding to the edge through-holes of the bottom frame 4 so as to be connected to the bottom frame 4 through the fixing pins 9.

[0022] The adjusting frame 13 is the core component for realizing the axial position adjustment function. Its main body is a disc-shaped structure, and the outer diameter of the disc is equal to the outer diameter of the bottom frame 4. The adjusting frame 13 is connected to the secondary sun gear 6 through spline connection, which can not only transmit torque but also drive the secondary sun gear 6 to move axially.

[0023] The fixing pin 9 is a high-strength bolt, and its specifications are selected according to the bearing capacity and size of the reducer. The length of the bolt should ensure that the bottom frame 4 and the top frame 12 can be firmly connected, and at the same time, sufficient pre-tightening force should be ensured after tightening to prevent loosening during the operation of the reducer.

[0024] When it is found that the planetary gear has an axial offset, by driving the adjusting frame 13 to move axially, since the secondary sun gear 6 is connected to the adjusting frame 13, the secondary sun gear 6 is driven to move up and down, forming a floating connection between the adjusting frame 13 and the top frame 12. In this way, the secondary sun gear 6 can automatically adjust its axial position to adapt to the axial offset of the planetary gear, ensure the normal meshing between gears, make the load evenly distributed on each planetary gear, and thus improve the transmission performance and stability of the reducer.

[0025] Please refer to Figure 2, An embodiment of driving the adjusting frame 13 to move axially adopts a lead screw pair structure. A lead screw penetrates and is connected to the surface thread of the top frame 12. One end of the lead screw is rotatably connected to the adjusting frame 13. By rotating the lead screw, through the thread action between the lead screw and the top frame 12, the axial movement of the lead screw is realized. The movement of the lead screw drives the axial movement of the adjusting frame 13. By setting a position sensor (such as a linear potentiometer) on the lead screw, the displacement of the adjusting frame 13 is fed back in real time to form a closed-loop control to ensure the axial adjustment accuracy. The adjusting frame 13 can also be directly fixedly connected to the flange at the end of the sun gear shaft through bolts to ensure the synchronous axial movement of the two. Two groups of symmetrically distributed linear guide posts 11 are arranged on the top frame 12, and linear bearings or sliders are installed at the corresponding positions of the adjusting frame 13 to form an axial sliding pair to limit the radial offset (the accuracy is controlled within 0.05 mm). Mechanical limit blocks are arranged at both ends of the stroke of the adjusting frame 13 and are combined with proximity switches to prevent over-adjustment from causing gear disengagement or jamming. The sun gear and the planet gear adopt crowned teeth or modified teeth to reduce the edge contact stress and adapt to the change in the meshing angle caused by slight axial offset. The adjusting frame 13 and the top frame 12 are made of high-strength aluminum alloy (such as 7075) or quenched and tempered steel (such as 42CrMo), and the surface of the linear guide post 11 is quenched (hardness HRC55 - 60) to improve the wear resistance. Force sensors are installed on both the first-stage planet carrier and the second-stage planet carrier 8. The force sensors are used to monitor the load of the planet gears. When it is directly detected by the force sensor (such as a piezoresistive micro sensor) that the load of a certain planet gear exceeds the limit, the axial positions of the sun gear or the planet gears need to be adjusted.

[0026] The floating design of the adjusting frame 13 enables the second-stage sun gear 6 to adjust its position according to the actual axial offset of the planet gears, improving the automation degree and reliability of the speed reducer.

[0027] By timely adjusting the axial position of the second-stage sun gear 6, good meshing between the gears is ensured, reducing the power loss caused by axial offset, thereby improving the transmission efficiency of the speed reducer.

[0028] The uniform load distribution reduces the local wear between the gears, and at the same time reduces the vibration and noise generated by poor meshing, prolongs the service life of the gears, and improves the working environment.

[0029] A positioning ring 10 is fixedly connected to the inner ring of the internal gear ring 5. The positioning ring 10 is located between the top frame 12 and the bottom frame 4. By setting the positioning ring 10, it is beneficial to fix the axial positions of the bottom frame 4 and the top frame 12. When installing the bottom frame 4 and the top frame 12, first place the top frame 12 on the upper end of the positioning ring 10, then place the bottom frame 4 on the lower end of the positioning ring 10, and then connect and fix them with fixing pins. Since the bottom frame 4 and the top frame 12 will rotate, in order to reduce the friction with the positioning ring 10, balls are arranged on the contact surfaces of the positioning ring 10 with the bottom frame 4 and the top frame 12 to convert the sliding friction into rolling friction.

[0030] For adjusting the axial position of the first-stage sun gear 2, the same method as that for the second-stage sun gear 6 can be adopted.

[0031] A plurality of uniformly distributed pin shafts 14 are provided on the surfaces of both the chassis 4 and the second-stage planet carrier 8. An axially adjustable assembly is provided on each pin shaft 14 to achieve independent or synchronous adjustment of the axial direction of the planet gears, ensuring axial alignment of the planet gears. The axially adjustable assembly includes a hollow shaft 3, an adjusting nut, and a locking nut. Each planet gear is connected to the hollow shaft 3 through a bearing. The hollow shaft 3 is sleeved on the pin shaft 14. An adjusting nut is provided on the inner surface of the inner ring of the hollow shaft 3. External threads are machined on the surface of the pin shaft 14. The pin shaft 14 passes through the adjusting nut movably and is threadedly connected to the adjusting nut. A locking nut is arranged at the bottom end of the pin shaft 14. The locking nut is threadedly connected to the pin shaft 14. The hollow shaft 3 is locked by pressing the hollow shaft 3 with the locking nut.

[0032] A two-stage planetary gear speed reducer includes a transmission structure and a housing 1. The housing 1 is of a split type and includes a front cover, a middle shell, and a rear cover, which are connected by bolts to ensure coaxiality. The internal gear ring 5 is fixed to the housing 1.

[0033] Specifically, in this solution: the input shaft drives the first-stage sun gear 2 to rotate. The first planet gear revolves and rotates on its own axis, driving the first-stage planet carrier to rotate. The first-stage planet carrier drives the second-stage sun gear 6, and then the second planet gear 7 revolves to drive the second-stage planet carrier 8 to output at low speed and high torque.

[0034] Place the top frame 12 on the upper end of the positioning ring 10, and place the chassis 4 on the lower end of the positioning ring 10, aligning the through holes at the edge of the chassis 4 with the threaded holes of the top frame 12. Use a fixing pin 9 to pass through the through hole and the threaded hole for connection, and tighten the bolts according to the specified torque to ensure a firm connection between the chassis 4 and the top frame 12, forming the basic framework of the first-stage planet carrier. Install the three first planet gears on the pin shafts 14 of the chassis 4 through bearings, ensuring that the planet gears can rotate freely around their own axes. Check that the bearings are installed in place without skewing. Fix the internal gear ring 5 in the housing 1, ensuring the accurate installation position of the internal gear ring 5 and the housing 1, and ensuring that the first planet gear meshes with the external teeth of the first-stage sun gear 2 and the internal teeth of the internal gear ring 5 at the same time to form a planetary transmission pair. Check the meshing clearance to ensure that it is within the design allowable range (generally 0.1 - 0.3 mm), and firmly connect it by bolts or fixing methods well-known to those skilled in the art. Connect the adjusting frame 13 coaxially with the second-stage sun gear 6, ensuring that torque can be transmitted and the second-stage sun gear 6 can be driven to move axially. Install the three second planet gears 7 on the pin shafts 14 of the second-stage planet carrier 8 through bearings, making the second planet gear 7 mesh with the external teeth of the second-stage sun gear 6 and the internal teeth of the internal gear ring 5 at the same time to form a second-stage planetary transmission pair. Use the second-stage planet carrier 8 as the output end of the system and rigidly connect it to the load through a flange, ensuring a firm flange connection and meeting the coaxiality requirements.

[0035] Turn on the power supply of the motor and conduct no-load trial operation. The operating speed starts from low speed and gradually increases to the rated speed. The operating time shall be no less than 30 minutes. Monitor the vibration and noise during the operation. The vibration amplitude shall not exceed 5 mm / s, and the noise decibel shall not exceed 85 dB(A). If any abnormality is found, stop the machine and check the gear meshing condition, bearing installation, etc. If it is found through the force sensor that the load of a certain planet gear is over-limit, manually operate the screw rod to drive the adjusting frame 13 to move axially, and adjust the axial position of the secondary sun gear 6 to make the load evenly distributed.

[0036] For the adjustment of the axial position of the primary sun gear 2, the same method as that of the secondary sun gear 6 is adopted, and it is adjusted according to the load condition of the planet gear. The adjustment of the axial position of the planet gear is as follows: by rotating the hollow shaft 3, through the threaded action between the adjusting nut and the pin shaft 14, the hollow shaft 3 moves axially, realizing the axial movement of the planet gear. After the adjustment is completed, tighten the locking nut to press against the hollow shaft 3 to achieve locking, ensuring that the planet gears are axially aligned. Turn on the power supply of the motor and start the motor according to the specified starting sequence. The input shaft drives the primary sun gear 2 to rotate. The first planet gear revolves and rotates around the primary sun gear 2, driving the primary planet carrier to rotate. The primary planet carrier drives the secondary sun gear 6, and then the second planet gear 7 revolves to drive the secondary planet carrier 8 to output at low speed and high torque. During the operation, ensure that the transmission direction is coaxial and in the same direction for input and output, without abnormal deviation. Check the connecting bolts of each component once every quarter, such as the connecting bolts between the chassis 4 and the top frame 12, the connecting bolts of each part of the machine shell 1, etc., and use a torque wrench to re-tighten them according to the specified torque to prevent loosening.

[0037] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A two-stage planetary gear transmission structure, comprising a primary sun gear (2), an inner ring gear (5), a primary planetary set, a primary planetary carrier, a secondary sun gear (6), a secondary planetary set, and a secondary planetary carrier (8), characterized in that: The primary sun gear (2) serves as a primary input end, and the secondary sun gear (6) serves as a secondary input end. Both the primary sun gear (2) and the secondary sun gear (6) can be floated to adjust the axial position.

2. A double-stage planetary gear transmission structure according to claim 1, characterized in that: The primary planetary frame comprises a bottom frame (4), a top frame (12) and an adjusting frame (13), and the bottom frame (4), the top frame (12) and the adjusting frame (13) rotate synchronously.

3. A double-stage planetary gear transmission structure according to claim 2, characterized in that: The inner ring of the inner gear ring (5) is fixedly connected to a positioning ring (10), and the positioning ring (10) is located between the top frame (12) and the bottom frame (4).

4. A double-stage planetary gear transmission structure according to claim 2, characterized in that: The surfaces of the base frame (4) and the secondary planetary frame (8) are both provided with a plurality of evenly distributed pins (14), and each of the pins (14) is provided with an axially adjustable component.

5. A double-stage planetary gear transmission structure according to claim 4, characterized in that: The first-stage planetary group comprises a plurality of evenly distributed first planetary gears, and the second-stage planetary groups each comprise a plurality of evenly distributed second planetary gears (7), and the first planetary gears and the second planetary gears (7) are both connected to the pin shaft (14) via an axially adjustable component.

6. A double-stage planetary gear transmission structure according to claim 1, characterized in that: The first-stage planet carrier and the second-stage planet carrier (8) are both equipped with force sensors, and the force sensors are used to monitor the load of the planetary gear.

7. A double-stage planetary gear transmission structure according to claim 3, characterized in that: Ball bearings are arranged on the contact surfaces between the positioning ring (10) and the bottom frame (4) and the top frame (12).

8. A two-stage planetary gear reducer, characterized in that: It comprises the transmission structure according to claim 1 and a housing (1), wherein the inner gear ring (5) is fixedly connected to the inner wall of the housing (1).

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