Hollow type speed reducer

Abstract

The application relates to a hollow type speed reducer which comprises a pin gear shell and a first stage speed reduction component and a second stage speed reduction component, the first stage speed reduction component comprises a driving wheel, a double gear and a planetary gear, the second stage speed reduction component comprises a plurality of eccentric shafts, two cycloid gears, a plurality of pin pins and an output shaft cover, the output shaft cover is rotationally arranged in the pin gear shell, and the planetary gear is connected to one end of the eccentric shaft; a cooling cavity is arranged in the eccentric shaft, the output shaft cover comprises an upper cover and a lower cover, the upper cover is arranged close to the planetary gear, annular liquid storage cavities are arranged on the sides adjacent to the upper cover and the lower cover, the two ends of the eccentric shaft are respectively and sealingly rotationally connected to the upper cover and the lower cover, and the two ends of the cooling cavity are respectively communicated with the two liquid storage cavities. According to the application, the cooling cavity is arranged in the eccentric shaft, circulation and flow of the cooling liquid between the cooling cavity and the liquid storage cavities can be formed when the speed reducer rotates forward and reversely, the annular liquid storage cavities facilitate heat dissipation of the cooling liquid, and the heat dissipation and temperature control effects of the eccentric shaft and the cylindrical cam thereon can be greatly improved.

Description

Technical Field

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

[0002] The hollow RV reducer is a new type of reducer developed based on the cycloidal pinwheel drive, and it is also a reducer with a unique structure among RV reducers. It features a two-stage reduction structure: the first stage is a planetary reduction structure, and the second stage is a cycloidal pinwheel reduction structure. Because the hollow type of reducer allows for the internal insertion of cables, it achieves a space-saving design. Furthermore, it has a higher number of meshing teeth, resulting in advantages such as high rigidity, overload resistance, small size, light weight, high precision, and low vibration, leading to its wider application in RV reducer applications.

[0003] Chinese patent application CN202410802708.2, in the related technology, proposes a hollow reducer for precision control, including a pin housing and two-stage reduction components placed therein: the first-stage reduction component includes a drive wheel on a servo motor, a double gear, and planetary gears. The double gear includes a driven wheel and a sun gear. The driven wheel meshes with the drive wheel, and the sun gear meshes with the planetary gears. The planetary gears are connected to the eccentric shaft extension end of the second-stage reduction component. A through-tube is provided in the inner hole of the double gear. The two sides of the double gear are supported by bearings on the right rigid disk and the corresponding positions of the robot body. The second-stage reduction component includes 2 to 3 evenly distributed eccentric shafts, a cycloidal wheel, a pin, a left rigid disk, and a right rigid disk.

[0004] However, after installing the conduit in the middle of the reducer, due to space constraints, it is difficult to arrange an eccentric shaft in the middle of the cycloidal wheel. This means that the eccentric rotation of the two cycloidal wheels can only be achieved by the eccentric shaft in the eccentric hole of the cycloidal wheel. As a result, the eccentric shaft in the eccentric hole needs to bear a greater torque, which makes the eccentric shaft more prone to overheating. This will not only accelerate the wear of the eccentric shaft, but also reduce the viscosity of the lubricating oil and aggravate the hardening failure of the rubber seal. Summary of the Invention

[0005] To address the issues of overheating caused by large loads on eccentrically arranged eccentric bearings, leading to eccentric shaft wear, reduced lubricant viscosity, and dynamic seal failure, this application provides a hollow type speed reducer.

[0006] The hollow type speed reducer provided in this application adopts the following technical solution:

[0007] A hollow reducer includes a pin gear housing, a first-stage reduction component, and a second-stage reduction component. The first-stage reduction component includes a drive wheel, a double gear, and planetary gears. The second-stage reduction component includes multiple eccentric shafts, two cycloidal wheels, multiple pins, and an output shaft cover. The output shaft cover is rotatably disposed within the pin gear housing. The planetary gears are connected to one end of the eccentric shafts. A cooling chamber is formed within the eccentric shafts. The output shaft cover includes an upper cover and a lower cover. The upper cover is disposed near the planetary gears. An annular liquid storage chamber is provided on the adjacent side of both the upper and lower covers. The two ends of the eccentric shaft are respectively sealed and rotatably connected to the upper and lower covers, and the two ends of the cooling chambers are respectively connected to the two liquid storage chambers.

[0008] Furthermore, the two cooling chambers with the longest straight-line distance on the radial cross-section of the needle-tooth shell are considered as a circulation group, and the two eccentric shafts in the same circulation group are respectively provided with spiral structures with opposite spiral directions on the walls of their cooling chambers.

[0009] Furthermore, the spiral structure includes spiral grooves formed on the wall of the cooling cavity or spiral blades fixed to the wall of the cooling cavity.

[0010] Furthermore, the eccentric shaft has a flat fan-shaped groove on the wall of its cooling cavity corresponding to the cylindrical cam protrusion on the eccentric shaft. The fan-shaped groove is connected to the cooling cavity, and the axial dimension of the fan-shaped groove along the eccentric shaft is no greater than one-fifth of the thickness of the cylindrical cam.

[0011] Furthermore, multiple sector-shaped slots are spaced apart along the eccentric shaft axis, and adjacent sector-shaped slots are staggered in the eccentric shaft axis.

[0012] Furthermore, the connection between the fan-shaped groove and the cooling cavity wall is designed to have a smooth transition.

[0013] Furthermore, the cylindrical cam protrusion on the eccentric shaft has heat-conducting fins embedded therein, extending into the cooling cavity.

[0014] Furthermore, the spiral structure includes spiral blades mounted on the wall of the cooling cavity. The spiral blades are made entirely or partially of shape memory alloy along the eccentric axis, or only the connection between the spiral blades and the wall of the cooling cavity is made of shape memory alloy. The phase transformation temperature of the shape memory alloy used is less than or equal to the maximum operating temperature of the lubricating oil in the reducer.

[0015] Furthermore, the cooling cavity end is configured to be constricted, with the large-diameter end located at the end of the eccentric shaft;

[0016] Alternatively, the end of the helical blade near the eccentric shaft end can be designed to be constricted, with the larger diameter end located at the end of the eccentric shaft.

[0017] Furthermore, the cooling cavity is provided with an enlarged portion at the location of the cylindrical cam near the eccentric shaft.

[0018] In summary, the beneficial technical effects of this application are as follows:

[0019] 1. By setting a cooling chamber in the eccentric shaft and connecting the two liquid storage chambers in the upper and lower covers through multiple cooling chambers, and by setting a spiral structure in the cooling chamber and making the spiral directions of the spiral structures in the two cooling chambers in the same circulation group opposite, even if the reducer of this application frequently reverses direction during operation, it will only cause the flow direction of the coolant in the cooling chamber of the eccentric shaft to reverse, and the coolant can always form a circulation between the cooling chamber and the liquid storage chamber. This can ensure that the coolant flowing to the cooling chamber of the eccentric shaft is always at a low temperature, thereby greatly improving the heat dissipation and temperature control effect on the eccentric shaft and its cylindrical cam.

[0020] 2. The heated coolant flowing out of the cooling chamber flows into the annular reservoir of the upper or lower cover. Since the upper and lower cover have a larger contact area with the external environment, the coolant in the annular reservoir can fully exchange heat with the external environment to reduce the temperature of the coolant in the reservoir and improve the cooling effect of the coolant.

[0021] 3. By setting a sector-shaped groove in the cylindrical cam that communicates with the cooling chamber, and by using the smooth transition of the connection between the sector-shaped groove and the cooling chamber, the coolant entering the sector-shaped groove can flow back to the cooling chamber along the smooth transition surface, regardless of whether the eccentric shaft is rotating forward or backward. This ensures that the coolant in the sector-shaped groove is also in a flowing state, thereby ensuring the heat dissipation and temperature control effect on the main working parts of the cylindrical cam.

[0022] 4. By setting the spiral blades to a multi-segment design and making the whole structure of shape memory alloy, the flow rate of the coolant in the cooling chamber can be dynamically adjusted autonomously according to the actual temperature of the coolant in the cooling chamber. That is, the flow and circulation of the coolant in the cooling chamber and the reservoir can be dynamically adjusted autonomously according to the working state of the reducer of this application, which can adapt to various working conditions of the reducer. Attached Figure Description

[0023] Figure 1 This is a cross-sectional structural diagram of an embodiment of this application;

[0024] Figure 2 This embodiment of the application is mainly used to illustrate the cross-sectional structure of a single eccentric shaft;

[0025] Figure 3 This is a cross-sectional structural diagram of the eccentric shaft according to an embodiment of this application;

[0026] Figure 4This is a cross-sectional schematic diagram of the heat-conducting fins arranged on the eccentric shaft in an embodiment of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1. Needle-tooth shell;

[0029] 21. Driving gear; 22. Double gear; 23. Planetary gear;

[0030] 3. Eccentric shaft; 31. Cooling cavity; 311. Enlarged section; 32. Sector groove; 33. Heat-conducting fins; 34. Cylindrical cam; 35. Through hole;

[0031] 41. Cycloidal wheel; 42. Pin;

[0032] 51. Top cover; 52. Bottom cover; 53. Liquid storage chamber;

[0033] 6. Spiral blades. Detailed Implementation

[0034] 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.

[0035] This application discloses a hollow type speed reducer. (Refer to...) Figure 1 and Figure 2 The device includes a pin housing 1, a first-stage reduction gear, and a second-stage reduction gear. The first-stage reduction gear includes a drive gear 21, a double gear 22, and a planetary gear 23. The second-stage reduction gear includes multiple eccentric shafts 3, two cycloidal wheels 41, multiple pins 42, and an output shaft cover. The output shaft cover is rotatably mounted inside the pin housing 1, and the planetary gear 23 is connected to one end of the eccentric shaft 3. Specifically, the first gear on the double gear 22 meshes with the drive gear 21, and the outer diameter of the first gear is larger than that of the drive gear 21. The second gear on the double gear 22 meshes with the planetary gear 23. A conduit is provided in the inner hole of the double gear 22, and it is rotatably mounted on the output shaft cover. Furthermore, the sealing bearing structure between the output shaft cover and the pin housing 1, the sealing bearing structure of the eccentric shaft 3 on the output shaft cover, and the bearing structure on the cycloidal wheels 41, as well as the assembly relationships of the aforementioned structures, are all existing technologies and can be fully implemented by those skilled in the art, so there is no need to elaborate further.

[0036] The main feature is that a cooling chamber 31 is formed along the axial direction inside the eccentric shaft 3. The inner diameter of the cooling chamber 31 does not exceed half the diameter of the main body of the eccentric shaft 3 to ensure the overall rigidity of the eccentric shaft 3. The output shaft cover includes an upper cover 51 and a lower cover 52 bolted together. Two cycloidal wheels 41 are assembled between the upper cover 51 and the lower cover 52. The upper cover 51 is located close to the planetary gear 23. An annular liquid storage chamber 53 filled with coolant is provided on the adjacent side of the upper cover 51 and the lower cover 52. The two ends of the eccentric shaft 3 are respectively sealed and rotatably connected to the upper cover 51 and the lower cover 52, and the two ends of the cooling chamber 31 are respectively connected to the two liquid storage chambers 53.

[0037] Accordingly, it should be noted that the rotary sealing structures at both ends of the eccentric shaft 3 and the two liquid storage chambers 53 are existing technologies, which can be fully implemented by those skilled in the art. For example, in a specific example, the end of the eccentric shaft 3 near the lower cover 52 has an extension that penetrates and extends into the liquid storage chamber 53 in the lower cover 52, and the outer wall of the extension is sealed to the lower cover 52 by a rotary seal; while the end of the eccentric shaft 3 near the upper cover 51, corresponding to the portion of the liquid storage chamber 53 in the upper cover 51, has multiple through holes 35 that communicate with the cooling chamber 31 in the eccentric shaft 3, and the eccentric shaft 3 also penetrates the upper and lower end faces of the upper cover 51 by rotary seals. This ensures a stable rotary sealing connection between the two ends of the eccentric shaft 3 on the upper cover 51 and the lower cover 52, and keeps the two liquid storage chambers 53 in communication with the multiple cooling chambers 31 on the multiple eccentric shafts 3.

[0038] Furthermore, the two cooling chambers 31 with the longest straight-line distance on the radial cross-section of the needle-tooth shell 1 constitute a circulation group. Within the same circulation group, the two eccentric shafts 3 each have a spiral structure with opposite spiral directions on the wall of their respective cooling chambers 31. The spiral structure includes spiral grooves formed on the wall of the cooling chamber 31 or spiral blades 6 fixed to the wall of the cooling chamber 31. The number of circulation groups depends on the total number of eccentric shafts 3 in the second-stage reduction component. Only one circulation group can be set, or multiple circulation groups can be set. Alternatively, if the total number of eccentric shafts 3 is odd, one circulation group can correspond to three cooling chambers 31, ensuring good circulation of the coolant in the liquid storage chambers 53 on the upper cover 51 and lower cover 52.

[0039] The working principle of this application will now be explained using 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 by this application; it is merely an example.

[0040] Specifically, refer to Figure 1 and Figure 2In this embodiment, the second-stage deceleration component is provided with four eccentric shafts 3. The cooling chambers 31 in the two eccentric shafts 3 arranged opposite each other and the two liquid storage chambers 53 in the upper cover 51 and the lower cover 52 can form a circulation channel. When the reducer of this application is working, the multiple eccentric shafts 3 rotate in the same direction and at the same speed between the upper cover 51 and the lower cover 52. When the eccentric shafts 3 rotate, the coolant can flow along the axial direction of the eccentric shafts 3 in the cooling chambers 31 by means of the spiral structure provided in the cooling chambers 31.

[0041] When the coolant flows in the cooling chamber 31 of the eccentric shaft 3, it can exchange heat and cool down the parts of the eccentric shaft 3 that generate a lot of heat, especially the parts corresponding to the two cylindrical cams 34 that frequently rub against the cycloidal wheel 41. This can effectively dissipate heat from the cylindrical cams 34 on the eccentric shaft 3, thereby suppressing problems such as wear of the cylindrical cams 34, reduction of lubricating oil viscosity, and failure of dynamic seals caused by overheating of the eccentric shaft 3. Furthermore, the heated coolant flowing out of the cooling chamber 31 flows into the annularly arranged liquid storage chamber 53 of the upper cover 51 or the lower cover 52. Since the end faces of the upper cover 51 and the lower cover 52 have a larger contact area with the external environment, the coolant in the annularly arranged liquid storage chamber 53 can fully exchange heat with the external environment, thereby reducing the temperature of the coolant in the liquid storage chamber 53 and improving the cooling effect of the coolant.

[0042] Subsequently, the cooled coolant, along with the rotation of the other eccentric shaft 3 in the same circulation group, enters the cooling chamber 31 of the eccentric shaft 3, where it dissipates heat and cools the eccentric shaft 3. The cooled coolant, after heat exchange and heating, then flows to the heat storage chamber of the lower cover 52 or upper cover 51 under the propulsive effect of the spiral structure in the cooling chamber 31, where it fully exchanges heat with the external environment. Thus, by setting up two storage chambers 53 and spiral structures in opposite directions in the same circulation group, it can be ensured that the coolant flowing into the cooling chamber 31 of the eccentric shaft 3 is always at a low temperature, thereby greatly improving the heat dissipation and temperature control effect on the eccentric shaft 3 and its cylindrical cam 34.

[0043] Furthermore, the circulation effect of the coolant between the cooling chamber 31 and the reservoir 53 is entirely dependent on the spontaneous generation of the eccentric shaft 3 during its operation, without the need for an external power source; and the faster the rotation speed of the eccentric shaft 3, the faster the flow speed of the coolant in the cooling chamber 31, the faster the circulation speed of the coolant, and the better the heat dissipation effect.

[0044] Moreover, even if the reducer of this application frequently reverses direction during operation, it will only cause the flow direction of the coolant in the cooling chamber 31 of the eccentric shaft 3 to reverse. The overall circulation effect in the heat storage chamber and the cooling chamber 31 remains unchanged, and the heat dissipation effect of the coolant can still be kept in a better state. This ensures that the reducer of this application can perform good heat dissipation and temperature control on the eccentric shaft 3 and the cylindrical cam 34 on it when operating in both forward and reverse directions.

[0045] In order to further improve the heat dissipation effect of the cylindrical cam 34 on the eccentric shaft 3.

[0046] In one feasible embodiment, refer to Figure 2 and Figure 3 The eccentric shaft 3 has a flat fan-shaped groove 32 on the wall of its cooling cavity 31 corresponding to the protrusion of the cylindrical cam 34 on the eccentric shaft 3. The fan-shaped groove 32 is connected to the cooling cavity 31, and the connection is designed as a smooth transition. The axial dimension of the fan-shaped groove 32 along the eccentric shaft 3 is no greater than one-fifth of the thickness of the cylindrical cam 34. Multiple fan-shaped grooves 32 are spaced apart along the axial direction of the eccentric shaft 3, and adjacent fan-shaped grooves 32 are staggered in the axial direction of the eccentric shaft 3. Figure 3 The solid line sector groove 32 and the dashed line sector groove 32 are shown.

[0047] Therefore, when the eccentric shaft 3 rotates, the coolant flows axially along the eccentric shaft 3 in the cooling chamber 31 by means of the spiral structure pushing the coolant. When the coolant flows to the sector groove 32, under the action of centrifugal force, the coolant also enters the sector groove 32, which can reliably and comprehensively exchange heat with the cylindrical cam 34, thereby significantly improving the heat dissipation effect of the cylindrical cam 34. Moreover, thanks to the smooth transition of the connection between the sector groove 32 and the cooling chamber 31, the coolant entering the sector groove 32 can flow back to the cooling chamber 31 along the smooth transition surface, regardless of whether the eccentric shaft 3 is rotating forward or backward, ensuring that the coolant in the sector groove 32 is also in a flowing state, thus ensuring the heat dissipation and temperature control effect of the main working parts of the cylindrical cam 34. Meanwhile, the staggered arrangement of multiple sector grooves 32 can ensure a large heat exchange area for the cylindrical cam 34, while also preventing the sector grooves 32 from having an excessive impact on the rigidity of the cylindrical cam 34. Similarly, the limitation of the axial dimension of the sector grooves 32 along the eccentric shaft 3 is also to avoid the cylindrical cam 34 having low rigidity and affecting the driving effect on the cycloidal wheel 41.

[0048] In another feasible embodiment, refer to Figure 4The cylindrical cam 34 on the eccentric shaft 3 has a protrusion in which heat-conducting fins 33 extend into the cooling cavity 31. Multiple heat-conducting fins 33 are provided, and their positions in the cooling cavity 31 should be arranged along the axial direction of the eccentric shaft 3. In this way, a gap is formed between two adjacent heat-conducting fins 33 for the coolant to pass through. The coolant can exchange heat well with the protrusion of the cylindrical cam 34 with the help of the good heat conduction effect of the heat-conducting fins 33. This can also significantly improve the heat dissipation effect of the cylindrical cam 34 and have less interference with the normal flow of coolant in the cooling cavity 31.

[0049] In other feasible embodiments, refer to Figure 2 Furthermore, an enlarged portion 311 can be provided in the cooling cavity 31 near the cylindrical cam 34 of the eccentric shaft 3. By providing the enlarged portion 311, the flow velocity of the coolant through the cooling cavity 31 in the corresponding area of ​​the cylindrical cam 34 can be slowed down to a certain extent, thereby maximizing the heat exchange time between the coolant and the cylindrical cam 34 and improving the heat dissipation effect. However, it should be clearly stated that the connection between the enlarged portion 311 and the adjacent cavity wall of the cooling cavity 31 must be set as a smooth transition surface to avoid creating excessive turbulence at the connection, which would affect the overall flow effect of the coolant in the cooling cavity 31.

[0050] Furthermore, in order to make the speed reducer of this application applicable to more and more complex working conditions.

[0051] In one embodiment, refer to Figure 1 and Figure 2 The spiral structure includes a spiral blade 6 installed on the wall of the cooling chamber 31. The spiral blade 6 is made of shape memory alloy in its entirety or in part along the eccentric shaft 3, or only the connection between the spiral blade 6 and the wall of the cooling chamber 31 is made of shape memory alloy. The phase transformation temperature of the shape memory alloy used is less than or equal to the maximum operating temperature of the lubricating oil in the reducer.

[0052] In this embodiment, the spiral blade 6 is a multi-segment design and is made entirely of shape memory alloy. The angle between the spiral blade 6 and the wall of the cooling cavity 31 is 25° to 35° in the low-temperature state (martensitic phase) and 40° to 50° in the high-temperature state (austenitic phase). Furthermore, the austenitic end temperature of the spiral blade 6 is slightly higher than the normal operating temperature of the coolant, for example, set at 70° to 80°.

[0053] Therefore, when the reducer of this application is in a stable working state, the frictional heat generated by the eccentric shaft 3 is small. At this time, the temperature of the coolant in the cooling chamber 31 is low, and the angle between the spiral blade 6 and the wall of the cooling chamber 31 is small. When the eccentric shaft 3 rotates, the spiral blade 6 rotates along with it, mainly to push the coolant to form a stable flow state in the cooling chamber 31, so as to realize the circulation of coolant in the cooling chamber 31 and the liquid storage chamber 53.

[0054] When the reducer of this application enters a high-load working state, the frictional heat generated by the eccentric shaft 3 increases, causing the temperature of the coolant flowing in the cooling chamber 31 to rise. When the coolant temperature rises to the phase transformation temperature of the spiral blade 6, the spiral blade 6 deforms, increasing the angle between it and the wall of the cooling chamber 31. This causes the free end of the spiral blade 6 to approach the central axis of the cooling chamber 31, thus increasing the disturbance effect on the coolant in the cooling chamber 31. At this time, when the spiral blade 6 rotates with the eccentric shaft 3, it mainly pushes a large amount of coolant to flow in the cooling chamber 31, which can increase the flow rate of coolant in the cooling chamber 31, thereby accelerating the circulation of coolant in the cooling chamber 31 and the reservoir 53. In other words, by using the spiral blade 6 made of shape memory alloy, the flow rate of coolant in the cooling chamber 31 can be dynamically adjusted autonomously according to the actual temperature of the coolant in the cooling chamber 31. That is, the circulation of coolant in the cooling chamber 31 and the reservoir 53 can be dynamically adjusted autonomously according to the working state of the reducer of this application, which can adapt to various working conditions of the reducer.

[0055] And refer to Figure 1 and Figure 2 The cooling chamber 31 is designed with a constricted end, with the larger diameter end located at the end of the eccentric shaft 3; or the spiral blade 6 is designed with a constricted end near the end of the eccentric shaft 3, with the larger diameter end located at the end of the eccentric shaft 3. Thus, when the coolant flows in the cooling chamber 31 in both forward and reverse directions, it first passes through the constricted structure at its end, which can accelerate the flow of the coolant and ensure the circulation speed of the coolant.

[0056] In another embodiment, both the upper cover 51 and the lower cover 52 are provided with quick connectors and valves that communicate with the two liquid storage chambers 53 respectively. These quick connectors allow direct connection to an external circulating cooling system, with one quick connector serving as the inlet and the other as the outlet. This allows for the replenishment of coolant from the external circulating cooling system, either to add or replace the coolant, or to continuously and rapidly promote the circulation of low-temperature coolant in the liquid storage chambers 53 and 31. Furthermore, in this embodiment, the spiral directions of the spiral structures within the same circulation group remain reversed to ensure that, without switching the outlet and inlet sections of the quick connectors, the reducer of this application can maintain the circulation of coolant in the liquid storage chambers 53 and 31 during both forward and reverse rotation.

[0057] 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.

[0058] 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 reducer, comprising a pin housing (1) and a first-stage reduction component and a second-stage reduction component, wherein the first-stage reduction component comprises a drive wheel (21), a double gear (22), and a planetary gear (23), and the second-stage reduction component comprises a plurality of eccentric shafts (3), two cycloidal wheels (41), a plurality of pins (42), and an output shaft cover, wherein the output shaft cover is rotatably disposed within the pin housing (1), and the planetary gear (23) is connected to one end of the eccentric shaft (3); characterized in that, The eccentric shaft (3) has a cooling chamber (31) inside. The output shaft cover includes an upper cover (51) and a lower cover (52). The upper cover (51) is located close to the planetary gear (23). An annular liquid storage chamber (53) is provided on the adjacent side of the upper cover (51) and the lower cover (52). The two ends of the eccentric shaft (3) are respectively sealed and rotatably connected to the upper cover (51) and the lower cover (52). The two ends of the cooling chamber (31) are respectively connected to the two liquid storage chambers (53). The two cooling chambers (31) with the longest straight-line distance on the radial cross-section of the needle-tooth shell (1) are taken as a circulation group. The two eccentric shafts (3) in the same circulation group are respectively provided with spiral structures with opposite spiral directions on the cavity wall of their cooling chambers (31); The eccentric shaft (3) has a flat fan-shaped groove (32) on the cavity wall of its cooling cavity (31) corresponding to the protrusion of the cylindrical cam (34) on the eccentric shaft (3). The fan-shaped groove (32) is connected to the cooling cavity (31). The axial dimension of the fan-shaped groove (32) along the eccentric shaft (3) is no greater than one-fifth of the thickness of the cylindrical cam (34).

2. The hollow reducer according to claim 1, characterized in that, The spiral structure includes a spiral groove formed on the wall of the cooling chamber (31) or a spiral blade (6) fixed to the wall of the cooling chamber (31).

3. A hollow reducer according to claim 1, characterized in that, The sector grooves (32) are provided at intervals along the axial direction of the eccentric shaft (3), and two adjacent sector grooves (32) are staggered in the axial direction of the eccentric shaft (3).

4. A hollow reducer according to claim 1, characterized in that, The connection between the fan-shaped groove (32) and the cavity wall of the cooling cavity (31) is configured as a smooth transition.

5. A hollow reducer according to claim 1, characterized in that, The cylindrical cam (34) on the eccentric shaft (3) has heat-conducting fins (33) embedded in its protrusion, which extend into the cooling cavity (31).

6. A hollow reducer according to claim 1, characterized in that, The spiral structure includes a spiral blade (6) installed on the wall of the cooling chamber (31). The spiral blade (6) is made of shape memory alloy in its entirety or in part along the eccentric shaft (3), or only the connection between the spiral blade (6) and the wall of the cooling chamber (31) is made of shape memory alloy. The phase transformation temperature of the shape memory alloy used is less than or equal to the maximum operating temperature of the lubricating oil in the reducer.

7. A hollow reducer according to claim 6, characterized in that, The cooling chamber (31) is designed with a constricted end and the large-diameter end is located at the end of the eccentric shaft (3); Alternatively, one end of the spiral blade (6) near the end of the eccentric shaft (3) is set in a constricted shape, and the large-diameter end is located at the end of the eccentric shaft (3).

8. A hollow reducer according to claim 1, characterized in that, The cooling chamber (31) is provided with an enlarged portion (311) near the cylindrical cam (34) of the eccentric shaft (3).

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