Joint drive

Abstract

This invention belongs to the technical field of robot joint drive equipment, specifically relating to a joint actuator, including a cycloidal reducer and a drive motor. The cycloidal reducer includes a reducer housing, an eccentric input shaft, a cycloidal wheel, and a piston. Pin teeth are arranged inside the reducer housing. The eccentric input shaft is connected to the drive motor. The cycloidal wheel is fitted onto the outside of the eccentric input shaft and meshes with the pin teeth. The cycloidal wheel has an axially penetrating pin hole, and a guide groove communicating with the pin hole is formed on its outer circumferential surface. A sliding groove penetrating the outer circumferential surface of the cycloidal wheel is formed on the inner wall of the guide groove. The piston is slidably assembled in the sliding groove and can only partially slide out when sliding outward. When the cycloidal wheel rotates, the piston extends outward under centrifugal force, increasing the space inside the guide groove. Lubricating grease enters the guide groove under compression. When the outer end of the piston rotates to abut against the reducer housing, it is pushed back and slides into the guide groove, pressing the grease accumulated in the guide groove into the pin hole, lubricating the friction mating parts between the pin hole and the pin shaft.

Description

Technical Field

[0001] This invention belongs to the technical field of robot joint drive devices, and specifically relates to a joint actuator. Background Technology

[0002] Existing robot joints widely use cycloidal pinwheel reducers to achieve high reduction ratio, small size, and high torque transmission output. The cycloidal reducer mainly relies on the drive motor and eccentric input shaft to drive the cycloidal wheel to perform planetary motion. The cycloidal wheel continuously meshes with the pin teeth on the inner side of the housing for transmission, and then the power output is completed through the engagement of the pin shaft and pin hole.

[0003] Under actual long-term operating conditions, there is high-frequency reciprocating extrusion and relative friction between the inner wall of the pin hole of the cycloidal wheel and the pin shaft, which is a core wear pair inside the reducer. Because the pin hole structure is closed and narrow, conventionally filled grease is difficult to remain stably, and insufficient replenishment and long-term insufficient lubrication can easily lead to abnormal wear, increased clearance, decreased transmission accuracy, and shortened service life.

[0004] Meanwhile, during the continuous operation of the cycloidal wheel, due to the centrifugal force of its own rotation, the grease in the inner cavity of the reducer housing tends to accumulate and deposit in large quantities on the inner wall of the housing and around the pin teeth. This accumulated grease cannot be spontaneously transported to the key friction area of ​​the pin hole, resulting in uneven distribution of the overall lubrication medium, local lubrication redundancy, and lack of oil at the key friction positions. This not only wastes lubrication resources but also fails to effectively solve the wear problem of the pin shaft and pin hole, making it difficult to meet the stable use requirements of robot joints under long-term, high-load, and high-precision conditions.

[0005] The methods described in this section are not necessarily methods that had been previously conceived or adopted. Unless otherwise specified, no method described in this section should be assumed to be prior art simply because it is included in this section. Similarly, unless otherwise specified, the issues mentioned in this section should not be considered to be accepted in any prior art. Summary of the Invention

[0006] To address the problems of insufficient lubrication and excessive wear in existing cycloidal reducers' pin holes, a joint actuator is provided to provide more reliable lubrication between the pin hole and the pin shaft.

[0007] To achieve the above objectives, one technical solution adopted by the present invention is: A joint actuator includes a cycloidal reducer and a drive motor; The cycloidal reducer includes: The reducer housing has several needle teeth arranged on its inner side; An eccentric input shaft is rotatably connected inside the reducer housing and is also connected to the drive motor. A cycloidal wheel is fitted on the outside of the eccentric input shaft and meshes with the needle teeth for transmission. The cycloidal wheel has an axially penetrating pin hole, and a guide groove communicating with the pin hole is opened on the outer circumferential surface of the cycloidal wheel. A sliding groove penetrating the outer circumferential surface of the cycloidal wheel is opened on the inner wall of the guide groove. The piston is slidably assembled in the groove along the sliding direction of the groove. A limiting structure is provided between the piston and the cycloidal wheel. The limiting structure is used to limit the maximum stroke of the piston sliding outward, so that the piston can only partially slide out of the groove. When the cycloidal wheel rotates, the piston is subjected to centrifugal force and slides outward along the sliding direction of the groove. When the cycloidal wheel rotates to the point where it is squeezed by the grease accumulated inside the reducer housing, the grease enters the guide groove. When the cycloidal wheel rotates to the point where the piston is pressed against the reducer housing, the piston slides inward along the slide groove into the guide groove, causing the grease in the guide groove to be squeezed into the pin hole.

[0008] Furthermore, both the guide channel and the chute are configured as straight channels extending in a straight line.

[0009] Furthermore, at the connection between the guide channel and the slide, the extension direction of the guide channel toward its outer peripheral surface opening forms an angle α with the extension direction of the slide toward its outer peripheral surface opening, and the angle α is less than 90°.

[0010] Furthermore, the piston has a limiting groove, and the limiting structure is configured as a limiting member, which extends into the limiting groove and is fixedly connected to the cycloidal wheel; The limiting component, in conjunction with the limiting groove, is used to limit the length of the piston sliding out of the groove.

[0011] Furthermore, the limiting groove extends through the piston along the cycloidal wheel axial direction, and limiting member slots are provided on both sides of the sliding groove. The two limiting member slots respectively extend to the corresponding axial end face of the cycloidal wheel. The limiting member is assembled in the two limiting member slots and extends through the limiting groove. The end of the piston used to slide out of the sliding groove is configured as a round head, and the cross-sectional shape of the piston perpendicular to its sliding direction is configured as a rectangle. Multiple pin holes are provided, and the multiple pin holes are distributed in a circular array around the axis of the cycloidal wheel.

[0012] Furthermore, the cycloidal reducer also includes an output shaft and a pin disposed on the output shaft, the pin engaging with the pin hole of the cycloidal wheel to transmit power; The reducer housing includes: A needle-tooth shell, with several needle teeth arranged on its inner side; The first flange is used to secure the pin tooth housing to the drive motor; The second flange is fixedly connected to the needle tooth shell on one side and rotatably connected to the output shaft on the other side.

[0013] Furthermore, the inner side of the output shaft is rotatably connected to the outer side of the eccentric input shaft via a first bearing.

[0014] Furthermore, a third flange is fixed to the side of the output shaft away from the cycloidal wheel, and the third flange is used to connect to an external load to transmit output power.

[0015] Furthermore, a fourth flange is fixedly connected to the outer edge of the third flange near the output shaft. The inner side of the fourth flange is rotatably connected to the outer side of the second flange through a second bearing to stabilize the outer edge of the third flange.

[0016] Furthermore, the third flange is fixedly connected to a wire guide cylinder that passes through the third flange, the output shaft, and the eccentric input shaft, and the drive motor has a wire guide groove adapted to the wire guide cylinder.

[0017] Compared with the prior art, the present invention has the following advantages: By installing a groove on the inner wall of the cycloidal wheel's guide channel and assembling a piston, the piston extends outward under centrifugal force when the cycloidal wheel rotates, creating space for grease to enter the guide channel. When the outer end of the piston rotates to abut against the reducer housing, it is pushed back and slides into the guide channel, pressing the grease accumulated in the guide channel into the pin hole. The process of grease entering the pin hole is directly driven by the reciprocating motion of the piston, making the entry more reliable. The outward stroke of the piston increases with the speed of the cycloidal wheel, and the amount of grease pressed into the pin hole when pushed back also increases. The lubrication supply is most sufficient when the pin hole friction is most intense under high-speed and high-load conditions, matching the lubrication supply with the operating conditions. This makes the joint actuator more stable under long-term, high-load conditions and reduces the wear of the pin hole and pin shaft. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of a joint actuator according to an embodiment of the present invention; Figure 2 This is a schematic cross-sectional view of a first embodiment of the joint actuator of the present invention; Figure 3 for Figure 2 Enlarged structural diagram at point A; Figure 4 This is an exploded view of one embodiment of the joint actuator of the present invention; Figure 5 This is a schematic diagram of a second cross-sectional structure of an embodiment of the joint actuator of the present invention; Figure 6for Figure 5 Enlarged structural diagram at point B; Figure 7 for Figure 6 Enlarged schematic diagram of the structure at point C; Figure 8 This is a schematic diagram of the cycloidal wheel in one embodiment of the joint actuator of the present invention; Figure 9 for Figure 8 Enlarged structural diagram at point D; Figure 10 for Figure 8 A magnified schematic diagram of the structure at point E in the middle.

[0019] The meanings of the labels in the attached diagram are as follows: Cycloidal reducer 1, reducer housing 11, pin tooth 111, pin tooth housing 112, first flange 113, second flange 114, eccentric input shaft 12, cycloidal wheel 13, guide groove 13a, pin hole 13b, slide groove 13d, limit member slot 13e, limit member 131, output shaft 14, pin shaft 141, first bearing 142, third flange 15, fourth flange 16, second bearing 17, wire guide cylinder 18, piston 19, limit groove 19a, drive motor 2, wire guide groove 2a. Detailed Implementation

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] Reference Figure 1 As shown, in this embodiment, the joint actuator disclosed in this invention includes a cycloidal reducer 1 and a drive motor 2. The cycloidal reducer 1 includes a reducer housing 11, an eccentric input shaft 12, a cycloidal wheel 13, and a piston 19.

[0022] The inner side of the reducer housing 11 is provided with several pin teeth 111, which are evenly distributed and used to mesh with the cycloidal wheel 13 for transmission. An eccentric input shaft 12 is rotatably connected inside the reducer housing 11, with one end connected to the drive motor 2, transmitting the power output from the drive motor 2 to the cycloidal wheel 13. The cycloidal wheel 13 is fitted onto the outer side of the eccentric input shaft 12 and meshes with the pin teeth 111 for transmission. Driven by the eccentric input shaft 12, it performs planetary motion, achieving speed reduction through meshing. The cycloidal wheel 13 has an axially penetrating pin hole 13b for engaging with a subsequent pin shaft 141 to achieve power output.

[0023] Reference Figure 5 , Figure 6 and Figure 7 As shown, the outer peripheral surface of the cycloidal wheel 13 is provided with a guide groove 13a that communicates with the pin hole 13b. The inner wall of the guide groove 13a is provided with a sliding groove 13d that penetrates the outer peripheral surface of the cycloidal wheel 13. The piston 19 is slidably assembled in the sliding groove 13d along the extension direction of the sliding groove 13d.

[0024] Please continue to refer to Figure 7 In this embodiment, the guide groove 13a extends from the outer peripheral surface of the cycloidal wheel 13 to the pin hole 13b, forming a fluid communication channel between the inner cavity of the reducer housing 11 and the pin hole 13b. The slide groove 13d is formed in the middle of the inner wall of the guide groove 13a and extends through to the outer peripheral surface of the cycloidal wheel 13, allowing the piston 19 to reciprocate radially within the slide groove 13d along the cycloidal wheel 13. A limiting structure is provided between the piston 19 and the cycloidal wheel 13, which limits the maximum outward stroke of the piston 19, ensuring that the piston 19 can only partially slide out of the slide groove 13d. In this embodiment, both the guide groove 13a and the slide groove 13d are configured as straight grooves extending in a straight line. The straight design reduces the flow resistance of the grease within the groove and facilitates machining.

[0025] Please continue to refer to Figure 7 In this embodiment, at the connection between the guide groove 13a and the slide groove 13d, an angle α is formed between the extending direction of the guide groove 13a toward its outer peripheral opening and the extending direction of the slide groove 13d toward its outer peripheral opening. The angle α is configured to be approximately 60 degrees. This angle setting ensures that when the piston 19 is pushed back, its end face does not directly face the inner cavity section of the guide groove 13a, but instead applies a thrust to the grease in the guide groove 13a in an oblique compression manner, allowing the grease to flow more smoothly along the direction of the guide groove 13a to the pin hole 13b. In addition, it allows the outer peripheral openings of the guide groove 13a and the slide groove 13d to form a gap of more than one tooth, so that the part of the cycloidal wheel 13 located between the two openings can retain sufficient material thickness, avoiding this area from becoming a weak point due to its narrow cross-section. The 60 degrees mentioned above is just an example. In other embodiments, the included angle α can be selected within the range of 30° to 80°. The specific value of the included angle α is preferably to ensure that the distance between the two openings is not less than one tooth pitch. When the included angle α is too small, the distance between the two openings is reduced, and the local strength of the cycloidal wheel 13 in this area decreases, but the deviation between the thrust direction and the extension direction of the guide channel 13a during pumping is smaller. When the included angle α is too large, the distance between the two openings increases, and the strength of the cycloidal wheel 13 in this area is more sufficient, but the pumping efficiency is reduced. The included angle α can be reasonably selected within the above range according to the actual number of teeth of the cycloidal wheel 13 and the structural space.

[0026] Please continue to refer to Figure 7In this embodiment, a limiting groove 19a is formed on the piston 19, and a limiting member 131 extending into the limiting groove 19a is fixedly connected to the cycloidal wheel 13. Under the constraint of the groove wall of the limiting groove 19a, the limiting member 131 restricts the maximum length of the piston 19 sliding out of the slide groove 13d, preventing the piston 19 from completely disengaging from the slide groove 13d under centrifugal force. The groove length of the limiting groove 19a determines the maximum outward extension of the piston 19, and thus determines the maximum change in volume of the guide groove 13a in each cycle. The groove length of the limiting groove 19a can be reasonably set according to lubrication requirements during design. The above-mentioned limiting through the cooperation of the limiting groove 19a and the limiting member 131 is only one example. In other embodiments, a groove can also be provided on the inner wall of the slide groove 13d, and a corresponding protrusion can be provided on the piston 19 to achieve limiting. All of the above-mentioned limiting structures belong to the limiting structures described in this invention. Their principle is to prevent the piston from completely disengaging from the slide groove through mechanical constraint. Those skilled in the art can choose according to the processing requirements.

[0027] Reference Figure 8 , Figure 9 and Figure 10 As shown, in this embodiment, the limiting groove 19a is provided through the piston 19 along the axial direction of the cycloidal wheel 13. The sliding groove 13d has limiting member slots 13e on each of its opposite sides. The two limiting member slots 13e penetrate the axial end faces of the corresponding sides of the cycloidal wheel 13. Thus, the limiting member 131 can be inserted axially from its axial end face, penetrating one limiting member slot 13e and then penetrating the limiting groove 19a before finally inserting into the other limiting member slot 13e. This assembly method allows the limiting member 131 to be subjected to force at both ends, resulting in strong stability after assembly. In this embodiment, the limiting member 131 is specifically a round shaft, which is pressed into the two limiting member slots 13e for fixation via an interference fit. The above-mentioned round shaft interference fit is only one example. In other embodiments, the limiting member 131 can also be in the form of a transverse screw, screwed into the limiting member slot 13e for fixation via a thread, making disassembly and assembly more convenient.

[0028] During operation, as the cycloidal wheel 13 undergoes planetary motion, the piston 19 slides outward along the slide groove 13d under the action of centrifugal force, partially extending outside the slide groove 13d. After the piston 19 slides outward, the inner end of the piston 19 exits the guide groove 13a, increasing the space within the guide groove 13a and providing space for the grease to enter the guide groove 13a. When the cycloidal wheel 13 rotates forward until the outer circumferential opening of the guide groove 13a is squeezed against the grease accumulated inside the reducer housing 11, the grease enters the guide groove 13a under the squeezing action. If the squeezing speed is fast, the grease is instantaneously compressed and quickly passes through the guide groove 13a, thus being directly sprayed into the pin hole 13b to participate in the lubrication between the pin hole 13b and the pin shaft 141. If the squeezing speed is slow, the grease is gradually compressed and slowly enters the guide groove 13a. The speed of the grease entering the pin hole 13b is insufficient to directly spray into the pin hole 13b, but it remains temporarily in the guide groove 13a. As the cycloidal wheel 13 continues to rotate in the forward direction, when the outer end of the piston 19 extending from the slide groove 13d rotates to abut against the inner wall of the reducer housing 11 or the pin tooth 111, the piston 19 is forced to slide back radially inward along the slide groove 13d by the squeezing action of the reducer housing 11. The inner end of the piston 19 re-enters the inner cavity of the guide groove 13a, causing the volume in the guide groove 13a to decrease rapidly. This pumps some of the accumulated grease into the pin hole 13b under a certain pressure, lubricating the friction mating parts between the pin hole 13b and the pin shaft 141.

[0029] Please continue to refer to Figure 7 and Figure 9 In this embodiment, the outer end of the piston 19 is configured with a rounded end. The arc surface of the rounded end guides the piston 19 to retract smoothly during the contact process, reducing jamming. The cross-sectional shape of the piston 19 perpendicular to its sliding direction is configured as rectangular. The rectangular cross-section prevents the piston 19 from rotating around its own axis within the slide groove 13d, ensuring stable sliding of the piston 19 along the slide groove 13d. The aforementioned rounded end is only one example. In other embodiments, ball bearings can also be embedded in the outer end of the piston 19 to change the sliding contact to a rolling contact.

[0030] In this embodiment, multiple pin holes 13b are provided, and the multiple pin holes 13b are distributed in a circular array around the axis of the cycloidal wheel 13. It should be understood that the number of pistons 19 can be set according to the number and arrangement position of the guide grooves 13a on the cycloidal wheel 13. Multiple pistons 19 are provided on the cycloidal wheel 13 and evenly distributed in the circumferential direction so that each pin hole 13b can be supplied with lubrication.

[0031] Reference Figure 2 , Figure 3 and Figure 4As shown, the cycloidal reducer 1 also includes an output shaft 14 and a pin 141 mounted on the output shaft 14. The pin 141 engages with the pin hole 13b of the cycloidal wheel 13 to transmit power. When the cycloidal wheel 13 performs planetary motion, the power is transmitted to the output shaft 14 through the engagement of the pin hole 13b and the pin 141, and then transmitted from the output shaft 14 to the external load. The reducer housing 11 includes a pin tooth housing 112, a first flange 113, and a second flange 114. A plurality of pin teeth 111 are arranged inside the pin tooth housing 112. The first flange 113 is used to fix the pin tooth housing 112 to the drive motor 2. One side of the second flange 114 is fixedly connected to the pin tooth housing 112, and the other side is rotatably connected to the output shaft 14, providing rotational support for the output shaft 14.

[0032] In this embodiment, the inner side of the output shaft 14 is rotatably connected to the outer side of the eccentric input shaft 12 via a first bearing 142, which reduces rotational friction between the two while ensuring coaxiality. The use of a deep groove ball bearing for the first bearing 142 is only one example. In other embodiments, needle roller bearings can also be used to obtain greater load-bearing capacity in situations where radial dimensions are limited, as long as the rotational support requirements are met.

[0033] Please continue to refer to Figure 3 A third flange 15 is fixedly connected to the output shaft 14 on the side away from the cycloidal wheel 13. The third flange 15 is used to connect to an external load to transmit output power. A fourth flange 16 is fixedly connected to the outer edge of the third flange 15 near the output shaft 14. The inner side of the fourth flange 16 is rotatably connected to the outer side of the second flange 114 via a second bearing 17, which supports the outer edge of the third flange 15 and makes the rotation of the third flange 15 more stable during power transmission. The type of the second bearing 17 can be selected according to the actual stress conditions, and it can be the same as or different from the first bearing 142.

[0034] In this embodiment, the third flange 15 is fixedly connected to a wire guide 18 that passes through the third flange 15, the output shaft 14 and the eccentric input shaft 12. The drive motor 2 has a wire guide groove 2a that is adapted to the wire guide 18. The cooperation between the wire guide 18 and the wire guide groove 2a is used to accommodate the connection wire harness of the joint actuator.

[0035] The joint actuator is used as follows: After connecting the drive motor 2 to an external power source, the power output by the drive motor 2 is transmitted to the eccentric input shaft 12 via a transmission connection. The eccentric input shaft 12 drives the cycloidal wheel 13 to perform planetary motion within the reducer housing 11. The cycloidal wheel 13 meshes with the pin gear 111 to achieve a speed reduction effect. During the rotation of the cycloidal wheel 13, the piston 19 extends outward along the slide groove 13d under the action of centrifugal force. The inner end of the piston 19 exits the guide groove 13a, increasing the space within the guide groove 13a and providing space for grease to enter. When the cycloidal wheel 13 rotates to the point where the outer circumferential opening of the guide groove 13a is squeezed against the grease accumulated in the reducer housing 11, the grease enters the guide groove 13a under the squeezing action. As the cycloidal wheel 13 continues to rotate until the outer end of the piston 19 abuts against the inner wall of the reducer housing 11, the piston 19 is pushed back into the slide groove 13d, and its inner end re-enters the guide groove 13a, reducing the volume of the guide groove 13a. This pumps the accumulated grease into the pin hole 13b at a certain pressure, lubricating the mating part between the pin hole 13b and the pin shaft 141. Through the mating of the pin hole 13b and the pin shaft 141, the cycloidal wheel 13 transmits the reduced power to the output shaft 14. The output shaft 14 drives the third flange 15 to rotate, thereby transmitting the power to the external load.

[0036] The lubrication performance of this joint actuator varies at different speeds. Under high-speed operation, the cycloidal wheel 13 rotates at a higher speed, resulting in greater centrifugal force on the piston 19 and a more complete outward extension stroke. This leads to a greater change in the volume of the guide groove 13a, allowing more grease to be pumped into the pin hole 13b with higher pumping pressure. The grease is forced into the deeper fit clearance between the pin hole 13b and the pin shaft 141, forming a thicker oil film. Simultaneously, the rapid compression speed of the grease at the outer circumferential opening of the guide groove 13a during high-speed operation causes instantaneous pressure on the grease, allowing some to directly pass through the guide groove 13a and be sprayed into the pin hole 13b, further increasing the oil supply per unit time. High speed and high load are precisely the conditions where friction between the pin hole 13b and the pin shaft 141 is most intense, and the oil film is most easily broken. The pumping capacity of the piston 19 increases with the rotational speed, perfectly matching the more urgent lubrication requirements under these conditions. Under low-speed operating conditions, the cycloidal wheel 13 rotates at a low speed, the centrifugal force on the piston 19 is small, the outward extension stroke is limited, the volume change of the guide groove 13a is small, and the pumping pressure is low. At this time, the grease is squeezed slowly, enters the guide groove 13a sequentially and is temporarily stored there, and is then slowly pushed back by the piston 19 and pumped into the pin hole 13b. Although the amount of grease pumped in each time is relatively small under low-speed conditions, the relative friction speed between the pin hole 13b and the pin shaft 141 is also low at low speeds, the oil film is squeezed out slowly, and the small oil supply is sufficient to maintain basic lubrication requirements.

[0037] In summary, this joint actuator, by setting a groove 13d on the inner wall of the guide groove 13a of the cycloidal wheel 13 and assembling a piston 19, utilizes the centrifugal force generated by the rotation of the cycloidal wheel 13 to drive the piston 19 to reciprocate, pumping the grease accumulated in the reducer housing 11 into the pin hole 13b at a certain pressure, thus ensuring better lubrication between the pin hole 13b and the pin shaft 141. Especially under high-speed and high-load conditions, the pumping capacity of the piston 19 increases with the rotation speed, making the lubrication supply more matched with the working conditions, thereby making the joint actuator more stable under long-term, high-load conditions.

[0038] In the description of this invention, the orientations or positional relationships involved (such as "upper," "lower," "left," "right," "inner," "outer," "axial," "radial," etc.) are all based on the orientations shown in the accompanying drawings and are only for ease of description. They do not imply that the device or component must be constructed or operated in a specific orientation and do not constitute a limitation on the invention. The terms "first" and "second" are used for descriptive purposes only and do not imply relative importance or the number of features; "a plurality" means at least two.

[0039] The terms "installation," "connection," and "fixation" should be interpreted broadly to encompass various situations, including fixed connections, detachable connections, or integral molding; mechanical connections or electrical connections; and direct connections or indirect connections through an intermediate medium. The term "above" or "below" another feature can refer to direct contact or indirect contact through an intermediate medium; "above" or "on top" includes directly above or diagonally above, or at a higher horizontal level; "below" or "under" includes directly below or diagonally below, or at a lower horizontal level.

[0040] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A joint actuator, characterized in that: Includes cycloidal reducers and drive motors; The cycloidal reducer includes: The reducer housing has several needle teeth arranged on its inner side; An eccentric input shaft is rotatably connected inside the reducer housing and is also connected to the drive motor. A cycloidal wheel is fitted on the outside of the eccentric input shaft and meshes with the needle teeth for transmission. The cycloidal wheel has an axially penetrating pin hole, and a guide groove communicating with the pin hole is opened on the outer circumferential surface of the cycloidal wheel. A sliding groove penetrating the outer circumferential surface of the cycloidal wheel is opened on the inner wall of the guide groove. The piston is slidably assembled in the groove along the sliding direction of the groove. A limiting structure is provided between the piston and the cycloidal wheel. The limiting structure is used to limit the maximum stroke of the piston sliding outward, so that the piston can only partially slide out of the groove. When the cycloidal wheel rotates, the piston is subjected to centrifugal force and slides outward along the sliding direction of the groove. When the cycloidal wheel rotates to the point where it is squeezed by the grease accumulated inside the reducer housing, the grease enters the guide groove. When the cycloidal wheel rotates to the point where the piston is pressed against the reducer housing, the piston slides inward along the slide groove into the guide groove, causing the grease in the guide groove to be squeezed into the pin hole.

2. The joint actuator according to claim 1, characterized in that, Both the guide channel and the chute are configured as straight channels extending in a straight line.

3. The joint actuator according to claim 2, characterized in that, At the junction of the guide channel and the chute, the extension direction of the guide channel toward its outer peripheral opening forms an angle α with the extension direction of the chute toward its outer peripheral opening, and the angle α is less than 90°.

4. The joint actuator according to claim 1, characterized in that, The piston has a limiting groove, and the limiting structure is configured as a limiting member, which extends into the limiting groove and is fixedly connected to the cycloidal wheel. The limiting component, in conjunction with the limiting groove, is used to limit the length of the piston sliding out of the groove.

5. The joint actuator according to claim 4, characterized in that, The limiting groove is provided to pass through the piston along the axial direction of the cycloidal wheel. The sliding groove has limiting member slots on both sides. The two limiting member slots are respectively connected to the corresponding axial end face of the cycloidal wheel. The limiting member is assembled in the two limiting member slots and passes through the limiting groove. The piston has a rounded end that slides out of the groove, and the piston has a rectangular cross-section perpendicular to its sliding direction. The pin holes are provided in a plurality of manner, and the plurality of pin holes are distributed in a circular array around the axis of the cycloidal wheel.

6. The joint actuator according to claim 1, characterized in that: The cycloidal reducer also includes an output shaft and a pin on the output shaft, the pin engaging with the pin hole of the cycloidal wheel to transmit power; The reducer housing includes: A needle-tooth shell, with several needle teeth arranged on its inner side; The first flange is used to secure the pin tooth housing to the drive motor; The second flange is fixedly connected to the needle tooth shell on one side and rotatably connected to the output shaft on the other side.

7. The joint actuator according to claim 6, characterized in that, The inner side of the output shaft is rotatably connected to the outer side of the eccentric input shaft via a first bearing.

8. The joint actuator according to claim 7, characterized in that: A third flange is fixed to the side of the output shaft away from the cycloidal wheel. The third flange is used to connect to an external load to transmit output power.

9. The joint actuator according to claim 8, characterized in that: A fourth flange is fixed to the outer edge of the third flange near the output shaft. The inner side of the fourth flange is rotatably connected to the outer side of the second flange through a second bearing to stabilize the outer edge of the third flange.

10. The joint actuator according to claim 9, characterized in that: The third flange is fixedly connected to a wire guide cylinder that passes through the third flange, the output shaft, and the eccentric input shaft, and the drive motor has a wire guide groove adapted to the wire guide cylinder.

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