Hollow type cycloid speed reducer for robot

Abstract

The application relates to a hollow type cycloid speed reducer for a robot, which comprises a supporting flange, an output flange and eccentric shafts, and the application comprises the following: two annular liquid cooling cavities are arranged inside the supporting flange and the output flange; an inner cooling cavity is arranged in the eccentric shaft and is arranged in the radial direction of the eccentric shaft; the two ends of the eccentric shaft are in sealed rotary connection with the supporting flange and the output flange respectively; the two ends of the inner cooling cavity are in communication with the two annular liquid cooling cavities respectively, and the interiors of the three are filled with cooling medium; spiral fins are arranged on the cavity wall of the inner cooling cavity of the eccentric shaft, and the spiral directions of the spiral fins in the two eccentric shafts are opposite; when the two eccentric shafts rotate in the same direction, the cooling medium circulates and flows between the two annular liquid cooling cavities through the two inner cooling cavities. When the eccentric wheel rotates, the spiral fins push the cooling medium in the inner cooling cavity to flow spirally along the axial direction, the eccentric shaft can be efficiently radiated, and the eccentric shaft can be effectively prevented from being deformed slightly and abraded on the surface due to overheating.

Description

Technical Field

[0001] This application relates to the technical field of speed reducers, and in particular to a hollow cycloidal speed reducer for robots. Background Technology

[0002] The RV (Rot-vector) transmission for robots (belonging to the crank-type closed differential gear train) is a new type of transmission developed on the basis of cycloidal pinwheel transmission. Its main characteristics are three major features (large transmission ratio, large load capacity, and large rigidity), two high features (high motion accuracy and high transmission efficiency), and one small feature (small backlash). Compared with simple cycloidal pinwheel planetary transmission, it has a smaller size and greater overload capacity, and the output shaft has high rigidity. Therefore, it has received widespread attention at home and abroad.

[0003] In the related technology, Chinese patent application CN202410157725.5 proposes a hollow internal meshing reducer for precision control, including an inner cycloidal gear ring and two-stage reduction components placed therein: the first-stage reduction component includes a drive wheel on a servo motor, a double gear and a planetary gear, and a through tube is provided in the inner hole of the double gear; the second-stage reduction component includes 2 to 3 evenly distributed eccentric shafts, cycloidal wheels, a left rigid disk and a right rigid disk, the cycloidal wheels are supported by bearings on the two eccentric sections of the eccentric shafts, the shaft extensions on both sides of the two eccentric sections of the eccentric shafts are supported by bearings in the peripheral holes of the left and right rigid disks, and the left and right rigid disks are supported by bearings in the inner holes on both sides of the inner cycloidal gear ring.

[0004] The hollow section of the aforementioned double gear is equipped with a conduit for threading cables or hydraulic lines, reducing the space occupied by peripheral equipment. However, for robot reducers, not only are high precision and low backlash required, but they also need to maintain good stability during long-term continuous operation. The power input of this cycloidal reducer for robots consists of multiple eccentric shafts that work in conjunction with the cycloidal wheel. These eccentric shafts need to withstand significant torque and friction, making them more prone to overheating. Conventional liquid cooling is insufficient to reach the shaft center. When the robot frequently outputs forward and reverse rotational power using the cycloidal reducer, the heat in the eccentric shafts cannot dissipate in time, easily leading to micro-deformation and surface wear within the shafts, ultimately affecting transmission accuracy. Summary of the Invention

[0005] In order to improve the problem of heat accumulation on the eccentric shaft of the cycloidal reducer for robots when frequently outputting forward and reverse rotational power, this application provides a hollow cycloidal reducer for robots.

[0006] This application provides a hollow cycloidal reducer for robots, employing the following technical solution:

[0007] A hollow cycloidal reducer for robots includes a pin tooth housing, a primary reduction component, a secondary reduction component, and an end cap. The end cap is fixedly connected to the pin tooth housing. The secondary reduction component includes a bolted-on support flange and an output flange, two eccentric shafts, two cycloidal wheels, and multiple pins located between them. The support flange and the output flange are rotatably mounted inside the pin tooth housing via bearings. The reducer also includes:

[0008] The low-speed tube has one end fixed to the hollow part of the output flange and extends from one end of the needle tooth shell to one end of the end cover, and the other end is rotatably mounted on the end cover. The input end of the first-stage reduction component is connected to the output end of the servo motor, and the output end is connected to the eccentric shaft.

[0009] There are two annular liquid cooling cavities, located inside the support flange and the output flange, respectively.

[0010] The internal cooling cavity is located inside the eccentric shaft and arranged radially thereon. The two ends of the eccentric shaft are respectively sealed and rotatably connected to the support flange and the output flange. The two ends of the internal cooling cavity are respectively connected to the two annular liquid cooling cavities and all three are filled with cooling medium.

[0011] Spiral fins are disposed on the cavity wall of the inner cooling chamber of the eccentric shaft, and the spiral directions of the spiral fins in the two eccentric shafts are opposite; when the two eccentric shafts rotate in the same direction, the cooling medium circulates between the two annular liquid cooling chambers through the two inner cooling chambers.

[0012] Furthermore, the spiral fins include:

[0013] Two fixing rings are provided and are respectively fixed to the cavity walls at both ends of the eccentric shaft;

[0014] The fin body is spiral-shaped and its two ends are respectively fixed to the two fixing rings. The fin body can deform axially and slide against the inner cooling cavity wall.

[0015] Furthermore, the fin body includes:

[0016] The elastic fin is located in the middle of the fin body and can be stretched or compressed along the axial direction of the fin body.

[0017] The shape memory alloy fin has two sections, which are respectively connected to the two ends of the elastic fin. The end of the shape memory alloy fin away from the elastic fin is fixed to the fixing ring. The pitch of the shape memory alloy fin in the martensitic phase is greater than that in the austenitic phase, and the phase transformation temperature of the shape memory alloy fin is less than the maximum operating temperature of the lubricating oil in the reducer.

[0018] Furthermore, the initial pitch of the elastic fin is between the pitch of the shape memory alloy fin in the martensitic phase and the pitch of the shape memory alloy fin in the austenitic phase.

[0019] Furthermore, the end of the eccentric shaft near the output flange is rotatably and sealed to the output flange, and the internal cooling cavity at that end of the eccentric shaft is flared outwards.

[0020] Furthermore, multiple disturbance blades are fixed to the cavity wall of the annular liquid cooling cavity on the side away from the supporting flange on the output flange, and the multiple disturbance blades are distributed in a circumferential array with equal spacing along the output flange axis.

[0021] Furthermore, the outer peripheral wall of the eccentric shaft near the supporting flange has multiple flow holes that communicate with the annular liquid cooling cavity on the supporting flange. Two sets of rotary seals are provided on the outer wall of the end of the eccentric shaft that penetrates the supporting flange. The two sets of rotary seals are arranged on both sides of the flow holes. The eccentric shaft is rotatably connected to the supporting flange through the two sets of rotary seals.

[0022] Furthermore, the first-stage reduction component includes:

[0023] The input shaft is used to connect to the output end of the servo motor, and a first gear is coaxially fixed on it.

[0024] A double gear is hollow and has a large sun gear and a small sun gear on it, wherein the large sun gear meshes with the first gear;

[0025] A planetary gear is coaxially fixed to one end of the eccentric shaft extending from the support flange, and the planetary gear meshes with the small sun gear.

[0026] Furthermore, both ends of the double gear are rotatably connected to the support flange and the end cover via bearings.

[0027] Furthermore, the low-speed tube penetrates the hollow part of the double gear, and an annular inner raceway is formed on the outer wall of the low-speed tube. An annular outer raceway is formed on the inner wall of the double gear. The openings of the annular inner raceway and the annular outer raceway are opposite to each other and together form an annular raceway. Multiple balls are arranged in the annular raceway, and the diameter of the balls is greater than the sum of the groove depths of the annular inner raceway and the annular outer raceway.

[0028] In summary, the beneficial technical effects of this application are as follows:

[0029] 1. When the cycloidal reducer of this application is working, the eccentric wheel rotates, and the spiral fins in the inner cooling cavity of the eccentric shaft push the cooling medium in the cavity to flow spirally along its axis, realizing the flow of the cooling medium in one annular liquid cooling cavity to another annular liquid cooling cavity. This can efficiently dissipate and cool the eccentric shaft at its core, which generates a lot of heat during the reducer's deceleration output. In conjunction with the lubricating oil filled inside the reducer, the eccentric shaft is cooled as a whole, which can effectively prevent micro-deformation and surface wear inside the eccentric shaft caused by overheating of the eccentric shaft.

[0030] 2. By setting the spiral directions of the spiral fins in the two eccentric shafts to opposite directions, the cooling medium flows in opposite directions in the two inner cooling cavities when the two eccentric shafts rotate simultaneously. This allows the cooling medium to circulate between the two annular liquid cooling cavities through the two inner cooling cavities, further improving the heat dissipation effect of the cooling medium on the eccentric shafts. Furthermore, the larger contact area between the output flange and the support flange and the external environment allows the cooling medium flowing into the annular liquid cooling cavity to fully exchange heat with the external environment, thereby reducing the temperature of the cooling medium in the annular liquid cooling cavity and improving the cooling effect of the cooling medium on the eccentric shafts.

[0031] 3. By setting the spiral fins as centrally located elastic fins and shape memory alloy fins at both ends, when the temperature of the cooling medium in the internal cooling cavity rises and exceeds the phase transformation temperature of the shape memory alloy fins, the shape memory alloy fins enter the austenitic phase. At this time, the main body of the spiral fins has a larger pitch in the middle and a smaller pitch at both ends. When the spiral fins with smaller pitch at the ends rotate with the eccentric shaft, they can significantly increase the axial flow velocity of the cooling medium in the internal cooling cavity, enhancing the convective heat transfer effect of the cooling medium. This allows the spiral fins in the eccentric shaft to dynamically adjust the pitch of the spiral fins in real time within the phase transformation temperature range of the shape memory alloy fins, following the temperature of the cooling medium in the internal cooling cavity. This achieves real-time matching between the cooling medium flow rate and heat dissipation requirements, reduces the temperature rise fluctuation of the eccentric shaft under different operating conditions, and ensures the long-term working stability of the eccentric shaft.

[0032] 4. When the pitch of the shape memory alloy fins is automatically adjusted according to the temperature of the cooling medium, the elastic fins between the shape memory alloy fins at both ends act as a mechanical buffer layer. This layer can absorb the volumetric strain generated by the phase transformation of the shape memory alloy fins and provide elastic recovery capability, thereby avoiding stress concentration and fracture at the root of the shape memory alloy fins and achieving smooth deformation of the entire spiral fin, thus ensuring its structural integrity.

[0033] 5. When the cycloidal reducer of this application frequently outputs forward and reverse deceleration rotational power, the eccentric shaft also frequently rotates forward and reverse. When the eccentric shaft reverses instantaneously, the cooling medium circulating in the inner cooling cavity will not immediately change its flow direction due to inertia. Instead, by utilizing the elastic axial expansion and contraction characteristics of the elastic fins in the spiral fins and the spiral path design of the spiral fins, the cooling medium can be buffered and guided, minimizing the impact of fluid inertial impact, avoiding transient flow turbulence in the inner cooling cavity during frequent forward and reverse rotation, and preventing sudden changes in the flow rate of the cooling medium.

[0034] 6. After the eccentric shaft reverses, the axial flow velocity in the inner cooling cavity after the spiral fins act on the cooling medium decreases by up to 50%. At the same time, the pumping force generated by the reverse rotation of the spiral fins also needs to overcome the inertia of the forward circulation of the cooling medium. In addition, the shape memory alloy fins in the spiral fins have a smaller pitch after the phase transformation due to temperature rise, which also reduces this reverse pumping force. As a result, even if the eccentric shaft reverses frequently during forward and reverse rotation, causing some cooling medium to flow back and form a reverse circulation, the net direction of the cooling medium's circulation in the two inner cooling cavities and the two annular liquid cooling cavities is still positive under the overall multi-frequency forward and reverse rotation conditions. That is, the cooling medium can always maintain a stable positive flow circulation, which can avoid the cooling interruption problem that may occur under frequent forward and reverse rotation conditions. Attached Figure Description

[0035] Figure 1 This is a schematic cross-sectional view of an embodiment of this application;

[0036] Figure 2 This is a partial cross-sectional structural diagram of an embodiment of this application;

[0037] Figure 3 This is a schematic diagram of the spiral fin in its initial state according to an embodiment of this application.

[0038] Explanation of reference numerals in the attached figures:

[0039] 11. Needle tooth housing; 12. End cap; 13. Low-speed tube;

[0040] 21. Support flange; 22. Output flange; 23. Annular liquid cooling cavity; 24. Disturbance blade;

[0041] 3. Eccentric shaft; 31. Internal cooling cavity; 32. Flow hole;

[0042] 41. Cycloidal wheel; 42. Pin;

[0043] 5. Spiral fin; 51. Fixing ring; 52. Fin body; 521. Elastic fin; 522. Shape memory alloy fin;

[0044] 61. Input shaft; 62. First gear; 63. Double gear; 64. Large sun gear; 65. Small sun gear; 66. Planetary gear;

[0045] 71. Annular outer raceway; 72. Annular inner raceway; 73. Ball bearings. Detailed Implementation

[0046] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] This application discloses a hollow cycloidal reducer for robots. (Refer to...) Figure 1 and Figure 2 It includes a needle tooth housing 11, a first-stage reduction component, a second-stage reduction component, and an end cap 12. The end cap 12 is fixed to the needle tooth housing 11 by multiple bolts or screws. The second-stage reduction component includes a bolted support flange 21 and an output flange 22, as well as two eccentric shafts 3, two cycloidal wheels 41, and multiple pins 42 located between them. The fixed support flange 21 and output flange 22 are rotatably installed in the needle tooth housing 11 in a back-to-back mounting manner through two angular contact bearings. The two ends of the eccentric shafts 3 are rotatably installed on the support flange 21 and the output flange 22 respectively through two tapered roller bearings. Other fitting and installation methods such as the cycloidal wheels 41, eccentric shafts 3, pins 42, and needle tooth housing 11 are all conventional technical means in the field, which can be fully implemented by those skilled in the art, and will not be elaborated further.

[0048] The cycloidal reducer in this application also includes:

[0049] The low-speed tube 13 is fixed at one end to the hollow part of the output flange 22 and extends from the end of the needle tooth shell 11 near the output flange 22 to one end of the end cover 12. The other end is rotatably mounted on the end cover 12. The input end of the first-stage reduction component is connected to the output end of the servo motor, and the output end is connected to the eccentric shaft 3.

[0050] Two annular liquid cooling chambers 23 are provided and are located inside the support flange 21 and the output flange 22, respectively.

[0051] The internal cooling cavity 31 is located inside the eccentric shaft 3 and is arranged radially thereafter. To ensure the torsional stiffness of the eccentric shaft 3, the diameter of the internal cooling cavity 31 is not greater than the radius of the eccentric shaft 3. The two ends of the eccentric shaft 3 are respectively sealed and rotatably connected to the support flange 21 and the output flange 22. The two ends of the internal cooling cavity 31 are respectively connected to two annular liquid cooling cavities 23, and all three are filled with a cooling medium. The cooling medium can be a modified ethylene glycol-based coolant, an organic acid coolant, or a high-cost phase change microcapsule suspension.

[0052] Spiral fins 5 are disposed on the cavity wall of the inner cooling cavity 31 of the eccentric shaft 3, and the spiral directions of the spiral fins 5 in the two eccentric shafts 3 are opposite; when the two eccentric shafts 3 rotate in the same direction, the cooling medium circulates between the two annular liquid cooling cavities 23 through the two inner cooling cavities 31.

[0053] Among them, reference Figure 1 and Figure 2 The first-stage reduction gear includes:

[0054] The input shaft 61 is used to connect to the output end of the servo motor, and the first gear 62 is coaxially fixed on it.

[0055] The double gear 63 is hollow and has a large sun gear 64 and a small sun gear 65 on it. The large sun gear 64 meshes with the first gear 62. Both ends of the double gear 63 are rotatably connected to the support flange 21 and the end cover 12 through bearings.

[0056] Planetary gear 66 is coaxially fixed to one end of the eccentric shaft 3 extending from the support flange 21, and planetary gear 66 meshes with small sun gear 65.

[0057] Therefore, when the cycloidal reducer of this application is working, the rotational motion output by the servo motor is reduced by the first-stage reduction component, and then further reduced by the cooperation of the eccentric wheel, cycloidal wheel 41, pin 42 and pin tooth housing 11, and finally output by the reduction tube on the output flange 22. During this process, when the double gear 63 rotates, it drives the two planetary gears 66 to rotate synchronously through the small sun gear 65, which in turn drives the two eccentric wheels to rotate synchronously. When the eccentric wheels rotate, the spiral fins 5 set in the inner cooling cavity 31 of the eccentric shaft 3 can push the cooling medium in its cavity to flow spirally along its axis, which can realize the flow of the cooling medium in one annular liquid cooling cavity 23 to another annular liquid cooling cavity 23. This can efficiently exchange and cool the eccentric shaft 3, which generates a lot of heat during the reduction motion output of the reducer. Together with the lubricating oil filled inside the reducer, it can dissipate heat from the eccentric shaft 3 as a whole, which can effectively avoid the micro-deformation and surface wear inside the eccentric shaft 3 caused by overheating of the eccentric shaft 3.

[0058] Furthermore, since the spiral fins 5 in the two eccentric shafts 3 have opposite spiral directions, such as one being left-handed and the other right-handed, when the two eccentric shafts 3 rotate simultaneously, the cooling medium in the two inner cooling cavities 31 flows in opposite directions, allowing the cooling medium to circulate between the two annular liquid cooling cavities 23 through the two inner cooling cavities 31. The output flange 22 and the support flange 21 have a larger contact area with the external environment, allowing the cooling medium flowing into the annular liquid cooling cavity 23 to fully exchange heat with the external environment, thereby reducing the temperature of the cooling medium in the annular liquid cooling cavity 23 and improving the cooling effect of the cooling medium on the eccentric shafts 3.

[0059] Furthermore, when the cycloidal reducer of this application is working, the output flange 22 and the support flange 21 rotate synchronously in the pin housing 11 and the end cover 12 to output low-speed rotational motion. This causes the cooling medium in the annular liquid cooling cavity 23 in the output flange 22 and the support flange 21 to circulate and also be disturbed in the annular liquid cooling cavity 23 with its rotational motion, which can further improve the cooling rate of the cooling medium in the annular liquid cooling cavity 23, thereby providing a better cooling effect for the eccentric shaft 3.

[0060] Therefore, when the cycloidal reducer of this application is working, the effect of the cooling medium circulating between the two internal cooling chambers 31 and the two annular liquid cooling chambers 23 depends entirely on the rotation of the eccentric shaft 3 during the working process. It can achieve the effect of self-heating and cooling of the eccentric shaft 3 without the need for an external power source.

[0061] Furthermore, a transparent viewing window and a filling port are provided on the outer wall of the output flange 22, which allows for easy and direct observation of the flow status and remaining amount of the cooling medium in the annular liquid cooling cavity 23 on the output flange 22; the cooling medium can also be replenished and replaced through the filling port.

[0062] Meanwhile, considering that the reducer body will inevitably heat up after the robot has been working for a long time, which increases the heat dissipation requirement of the eccentric shaft 3, the following improvements are made to ensure the stability of the vulnerable component eccentric shaft 3 and to ensure the long-term stable operation of the cycloidal reducer of this application and the robot using the reducer.

[0063] Reference Figure 2 and Figure 3 The spiral fin 5 of this application includes:

[0064] Two fixed rings 51 are provided and are respectively fixed to the cavity walls at both ends of the eccentric shaft 3;

[0065] The fin body 52 is spiral-shaped and its two ends are fixed to two fixing rings 51 respectively. The fin body 52 can deform axially and slide against the cavity wall of the inner cooling cavity 31.

[0066] Specifically, the fin body 52 includes:

[0067] The elastic fin 521 is located in the middle of the fin body 52 and can be stretched or compressed along the axial direction of the fin body 52; it is specifically made of spring steel or beryllium copper alloy.

[0068] The shape memory alloy fin 522 has two sections, each connected to one end of the elastic fin 521. The end of the shape memory alloy fin 522 furthest from the elastic fin 521 is fixed to the retaining ring 51. The pitch of the shape memory alloy fin 522 in the martensitic phase is greater than its pitch in the austenitic phase, and the phase transformation temperature of the shape memory alloy fin 522 is lower than the maximum operating temperature of the lubricating oil in the reducer, typically 80℃. Furthermore, the initial pitch of the elastic fin 521 is between the pitch of the shape memory alloy fin 522 in the martensitic phase and the pitch of the shape memory alloy fin 522 in the austenitic phase. Figure 3 As shown, in the initial state, the pitch of the elastic fin 521 is smaller than the pitch of the shape memory alloy fin 522 in the martensitic phase.

[0069] The working process of the fin body 52 will now be described in a common application scenario. It should be noted that this common implementation scheme should not be used as the basis for determining the essential features for understanding the technical problem claimed to be solved in this application; it is merely an example.

[0070] For example, in a specific instance, the pitch of the shape memory alloy fin 522 in the martensitic phase (low temperature state) is 12mm, which can be adapted to low-speed / cold start conditions and can increase the flow channel cross-sectional area and reduce flow resistance when rotating with the eccentric shaft 3; the pitch of the shape memory alloy fin 522 in the austenitic phase (high temperature state) is 8mm, which can be adapted to high-speed / high-load conditions and can enhance pumping force and turbulent heat transfer when rotating with the eccentric shaft 3; and the phase transformation temperature of the shape memory alloy fin 522 is set to 60℃~75℃; and the pitch of the elastic fin 521 in the initial state is 10mm.

[0071] Thus, when the cycloidal reducer of this application is in a cold start or low-speed working state, the frictional heat generated by the eccentric shaft 3 is small. At this time, the temperature of the cooling medium in the inner cooling cavity 31 is low, and the shape memory alloy fins 522 are still in the martensitic phase. At this time, the fin body 52 in the spiral fin 5 has a small pitch in the middle and a large pitch at both ends. The spiral fins 5 with large pitch at the ends have small flow resistance when rotating with the eccentric shaft 3, which can adapt to the low flow heat dissipation requirements of robot joints during low-speed operation or cold start, and avoid the grease sticking in the reducer due to overcooling.

[0072] When the cycloidal reducer of this application operates at high speed or high load, the heat generated by the eccentric shaft 3 increases, and the temperature of the cooling medium in the inner cooling cavity 31 rises. When the temperature rises to the phase transformation temperature of the shape memory alloy fins 522, the shape memory alloy fins 522 enter the austenitic phase. At this time, the fin body 52 in the spiral fin 5 has a large pitch in the middle and a small pitch at both ends. When the spiral fins 5 with small pitch at the ends rotate with the eccentric shaft 3, they can significantly increase the axial flow velocity of the cooling medium in the inner cooling cavity 31, and enhance the convective heat transfer effect of the cooling medium. This allows the spiral fins 5 in the eccentric shaft 3 to dynamically adjust the pitch of the spiral fins 5 in real time within the phase transformation temperature range of the shape memory alloy fins 522, in accordance with the temperature of the cooling medium in the inner cooling cavity 31. This achieves real-time matching between the cooling medium flow rate and heat dissipation requirements, reduces the temperature rise fluctuation of the eccentric shaft 3 under different operating conditions, and ensures the long-term working stability of the eccentric shaft 3.

[0073] Moreover, when the pitch of the shape memory alloy fin 522 is automatically adjusted according to the temperature of the cooling medium, the elastic fin 521 located between the shape memory alloy fins 522 at both ends acts as a mechanical buffer layer, which can absorb the volume strain generated by the phase transformation of the shape memory alloy fin 522 and provide elastic recovery capability, avoid stress concentration and fracture at the root of the shape memory alloy fin 522, and achieve smooth deformation of the entire spiral fin 5, ensuring its structural integrity.

[0074] Furthermore, when the cycloidal reducer of this application frequently outputs forward and reverse deceleration rotational power, the eccentric shaft 3 also frequently rotates forward and reverse. Taking the forward circulation of the cooling medium in the two inner cooling chambers 31 and the two annular liquid cooling chambers 23 when the eccentric shaft 3 rotates forward as an example, when the eccentric shaft 3 instantly reverses, the cooling medium circulating in the inner cooling chamber 31 will not immediately change its flow direction due to inertia. Instead, with the help of the elastic axial expansion and contraction characteristics of the elastic fins 521 in the spiral fins 5 and the spiral path design of the spiral fins 5, the cooling medium can be buffered and guided, minimizing the impact of fluid inertia and avoiding transient flow turbulence in the inner cooling chamber 31 during frequent forward and reverse rotation, thus preventing sudden changes in the flow rate of the cooling medium.

[0075] Moreover, after the eccentric shaft 3 reverses, the axial flow velocity in the inner cooling cavity 31 after the spiral fins 5 act on the cooling medium decreases by up to 50%. At the same time, the pumping force generated by the reverse rotation of the spiral fins 5 also needs to overcome the inertia of the forward circulation of the cooling medium. In addition, the pitch of the shape memory alloy fins 522 in the spiral fins 5 decreases after the phase transformation due to temperature rise, which also reduces the reverse pumping force. As a result, even if the eccentric shaft 3 reverses during the process of frequent forward and reverse rotation, the reverse rotation of the eccentric shaft 3 will cause some cooling medium to flow back and form a reverse circulation. However, under the overall multi-frequency forward and reverse rotation conditions, the net direction of the circulation flow of the cooling medium in the two inner cooling cavities 31 and the two annular liquid cooling cavities 23 is still positive. That is, the cooling medium can always maintain a stable positive flow circulation, which can avoid the cooling interruption problem that may occur under frequent forward and reverse rotation conditions.

[0076] In addition, refer to Figure 1 and Figure 2 The eccentric shaft 3 is rotatably connected to the output flange 22 at one end near the output flange 22, and the inner cooling cavity 31 of the eccentric shaft 3 at this end is flared outward. Furthermore, multiple disturbance blades 24 are fixedly attached to the cavity wall of the annular liquid cooling cavity 23 on the side away from the supporting flange 21 on the output flange 22. The multiple disturbance blades 24 are distributed in a circumferential array with equal spacing along the axial direction of the output flange 22.

[0077] Therefore, by setting multiple disturbance blades 24 in the output flange 22, the disturbance of the cooling medium in the annular liquid cooling cavity 23 of the output flange 22 can be further promoted, the heat exchange efficiency between the cooling medium and the external environment in the annular liquid cooling cavity 23 can be improved, and the heat dissipation effect of the cooling medium on the eccentric shaft 3 can be ensured.

[0078] At the same time, refer to Figure 1 and Figure 2 The outer peripheral wall of the eccentric shaft 3 near the support flange 21 has multiple flow holes 32 that communicate with the annular liquid cooling cavity 23 on the support flange 21. The outer peripheral wall of the end of the eccentric shaft 3 that passes through the support flange 21 is provided with two sets of rotary seals. The two sets of rotary seals are arranged on both sides of the flow holes 32. The eccentric shaft 3 is sealed and rotated with the support flange 21 through the two sets of rotary seals.

[0079] Furthermore, the low-speed tube 13 penetrates the hollow portion of the double gear 63. An annular inner raceway 72 is formed on the outer wall of the low-speed tube 13, and an annular outer raceway 71 is formed on the inner wall of the double gear 63. The openings of the annular inner raceway 72 and the annular outer raceway 71 face each other and together form an annular raceway. Multiple balls 73 are disposed within the annular raceway, and the diameter of the balls 73 is greater than the sum of the groove depths of the annular inner raceway 72 and the annular outer raceway 71. In a specific configuration, the outer wall of the double gear 63 is provided with a maintenance port for installing the balls 73, and the maintenance port is closed by a bolted baffle.

[0080] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," "third," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" and similar terms mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude other elements or objects. "Above," "below," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0081] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A hollow type cycloid speed reducer for a robot, comprising a pin gear shell, a primary speed reduction component, a secondary speed reduction component and an end cover, the end cover being fixedly connected with the pin gear shell, the secondary speed reduction component comprising a bolted fixed support flange and an output flange and two eccentric shafts, two cycloid wheels and a plurality of pin pins located between the two, the support flange and the output flange being rotatably mounted in the pin gear shell through bearings, characterized in that, Also include: Low-speed pipe, one end fixed in the output flange hollow and from the pin tooth shell one end to the end cover one end, the other end is installed on the end cover, the input end of the first reduction component and the output end of the servo motor transmission connection, the output end and the eccentric shaft transmission connection; Annular liquid cooling cavity, provided with two and respectively located in the support flange and the output flange inside; Internal cooling cavity, provided in the eccentric shaft and along its radial direction, the eccentric shaft both ends are respectively sealed with the support flange and the output flange rotation connection, the internal cooling cavity both ends are respectively communicated with two annular liquid cooling cavity and three inside are filled with cooling medium; Spiral fin, provided on the cavity wall of the eccentric shaft internal cooling cavity, and the spiral direction of the spiral fin in two eccentric shafts is opposite; when two eccentric shafts rotate in the same direction, the cooling medium circulates through two internal cooling cavities between two annular liquid cooling cavities.

2. The hollow type cycloid speed reducer for robots according to claim 1, characterized in that, The spiral fin includes: Fixed ring, provided with two and respectively fixed on the cavity wall of the eccentric shaft both ends; Fin body, spiral shape and both ends are respectively connected with two fixed rings, the fin body can be deformed in the axial direction and slide on the cavity wall of the internal cooling cavity.

3. The hollow type cycloid speed reducer for robots according to claim 2, characterized in that, The fin body includes: Elastic fin, provided in the middle of the fin body, which can be stretched or compressed in the axial direction of the fin body; Shape memory alloy fin, provided with two sections and connected to the two ends of the elastic fin, the end of the shape memory alloy fin away from the elastic fin is fixed with the fixed ring; the pitch of the shape memory alloy fin in martensite phase is greater than that in austenite phase, and the phase transition temperature of the shape memory alloy fin is less than the maximum working temperature of the lubricating oil in the speed reducer.

4. The hollow type cycloid speed reducer for robots according to claim 3, characterized in that, The initial pitch of the elastic fin is between the pitch of the shape memory alloy fin in martensite phase and the pitch of the shape memory alloy fin in austenite phase.

5. The hollow type cycloid speed reducer for robots according to claim 1, wherein The end of the eccentric shaft close to the output flange is sealed and rotationally connected to the output flange, and the internal cooling cavity of the eccentric shaft at the end is outwardly flared.

6. The hollow type cycloid speed reducer for robots according to claim 1, wherein A plurality of disturbance vanes are fixed on the cavity wall of the annular liquid cooling cavity away from the support flange on the output flange, and the plurality of disturbance vanes are distributed in an equidistant circumferential array along the axial direction of the output flange.

7. The hollow type cycloid speed reducer for robot according to claim 1, characterized in that, A plurality of flow holes are provided on the outer peripheral wall of the eccentric shaft close to the support flange and communicated with the annular liquid cooling cavity on the support flange, two groups of rotary sealing elements are provided on the end outer wall of the support flange through which the eccentric shaft penetrates, and the two groups of rotary sealing elements are arranged on both sides of the flow holes, and the eccentric shaft is sealed and rotationally connected with the support flange through the two groups of rotary sealing elements.

8. The hollow type cycloid speed reducer for robots according to claim 1, characterized in that, The first reduction component includes: Input shaft, for connecting with the output end of the servo motor, a first gear is coaxially fixed on the input shaft; Double gear, hollow, provided with a large sun gear and a small sun gear, the large sun gear is meshed with the first gear; Planetary gear, coaxially fixed on the end of the eccentric shaft protruding from the support flange, the planetary gear is meshed with the small sun gear.

9. The hollow type cycloid speed reducer for a robot according to claim 8, wherein Both ends of the double gear are rotationally connected to the support flange and the end cover through bearings.

10. The hollow type cycloid speed reducer for a robot according to claim 8, wherein The low-speed pipe penetrates the double gear hollow part, the outer wall of the low-speed pipe is provided with an annular inner raceway, the inner wall of the double gear is provided with an annular outer raceway, the annular inner raceway and the annular outer raceway are opposite to each other and together form an annular raceway, a plurality of balls are arranged in the annular raceway, and the diameter of the ball is greater than the sum of the groove depths of the annular inner raceway and the annular outer raceway.

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