Electro-hydraulic hybrid driving cycloid motor for humanoid robot joint motor

Abstract

The application belongs to the technical field of humanoid robot driving, and particularly relates to an electro-hydraulic hybrid driving cycloidal motor for a humanoid robot joint motor, which comprises a motor rotor, the motor rotor is connected with an inner rotor through a spline, the inner rotor is uniformly distributed with inner needle teeth on a circumference, an outer rotor is arranged on one side of the inner needle teeth, an oil cavity is arranged around the surface of the inner needle teeth and the inner contour of the outer rotor, an outer needle tooth is arranged on one side of the outer rotor, a middle shell is arranged on one side of the outer needle tooth, a low-pressure oil cavity is arranged around the outer contour of the outer rotor, the surface of the outer needle tooth and the inner diameter of the middle shell, a motor stator silicon steel sheet is embedded on the middle shell, fractional slot concentrated winding is wound on the upper end of the motor stator silicon steel sheet, and a permanent magnet and a magnetic bridge are embedded in the inner part of the outer rotor. The application adopts a novel permanent magnet brushless direct current motor topology structure, i.e. a permanent magnet composite motor with a cycloidal pair structure, which changes a traditional stator-rotor relative circumferential motion pair into a cycloidal pair, generates a planetary motion track of a rotor, and realizes integration of hydraulic energy and electromagnetic energy.

Description

Technical Field

[0001] This invention relates to the field of humanoid robot drive technology, specifically to an electro-hydraulic hybrid drive cycloidal motor for humanoid robot joint motors. Background Technology

[0002] Electric drive systems (motor + reducer) are currently the mainstream choice for humanoid robots. Taking elbow joint motors as an example, for mass-produced elbow joint motors for humanoid robots to truly become a reality within the next two years, they need to simultaneously meet two crucial requirements: "sufficient torque" and "high torque density." Otherwise, they will either be unable to lift everyday items or their weight / cost will remain high. Currently, mass-produced elbow joint motors must at least meet the requirements of "peak torque ≥ 100 Nm and peak torque density ≥ 100 Nm / kg" to stably complete light-load tasks such as "holding a water cup."

[0003] The existing technology has the following defects or problems:

[0004] Existing motors used in humanoid robot joints, even after a single-stage reduction, can only achieve a peak torque density of 80-90 Nm / kg. This is still far from meeting the target of bearing heavy loads. The main reason for this is that electric drive joint motors face the following three core bottlenecks:

[0005] 1. Torque density ceiling:

[0006] Existing high-performance frameless torque motors have a rated torque density of approximately 20-30 Nm / kg. After adding a harmonic reducer, the system's rated torque density drops to 10-15 Nm / kg. In contrast, hydraulic drives, with their hydraulic motor + cylinder system, can achieve a rated torque density of 100-200 Nm / kg, which is 6-10 times that of electric drives. The fundamental reason for the ceiling in motor torque density is that motor torque has a square relationship with volume (T∝D²L), while hydraulic systems can achieve linear force amplification through fluid pressure (typically 20-30 MPa). Furthermore, electric drives rely on high reduction ratios (such as 100:1 harmonic reducers) to increase torque, but this leads to difficulties in reverse drive and efficiency losses (mechanical efficiency is typically only 60%-80%).

[0007] 2. Dynamic response and overload capacity:

[0008] Electric drive systems have limited bandwidth, constrained by the rotational inertia of the motor rotor. Force control bandwidth is typically <100Hz, while hydraulic drives can reach 200~500Hz (closer to the response speed of biological muscles). In addition, electric motors have limited instantaneous overload capacity: the peak torque of an electric motor is typically 3~5 times the rated value, and the duration is short (<1 second), while hydraulic systems can achieve 10 times instantaneous overload through accumulators.

[0009] 3. Thermal management challenges

[0010] When high torque is output or the speed changes rapidly, the motor experiences high copper and iron losses, leading to rapid winding temperature rise and severe motor overheating, requiring liquid cooling for heat dissipation. In contrast, hydraulic systems can dissipate heat naturally through oil circulation.

[0011] The above three core bottlenecks are important obstacles to the development of humanoid robots, which will lead to the following problems: (1) Limited load capacity. Insufficient torque will directly affect the load-bearing capacity of the joints, causing the robot to be unable to bear its own weight or external loads, and is prone to imbalance and falls in scenarios such as walking and carrying. (2) Decreased motion accuracy. When the joint motor torque and bandwidth are insufficient, the mechanism may not be able to complete the predetermined action normally, resulting in position deviation or inaccurate motion trajectory, especially in scenarios that require high-precision control (such as micro-operations or fine movements). (3) Reduced efficiency and shortened lifespan. Insufficient torque may cause the motor to run under high load continuously and be in an overloaded state for a long time, which will accelerate the internal mechanical wear and shorten the service life. In addition, the motor heats up severely, increasing energy consumption and reducing the overall system efficiency. (4) Increased pressure on the control system. When the motor output torque is insufficient to maintain joint stability, the control system needs to compensate for the error through algorithms, increasing the computational complexity, which may lead to response delay or loss of control risk. For example, if the leg driving force is insufficient when walking, the posture needs to be adjusted more frequently to maintain balance.

[0012] It should be noted that the above content falls within the inventor's technical knowledge and does not necessarily constitute prior art. Summary of the Invention

[0013] To address the shortcomings of existing technologies, this invention provides an electro-hydraulic hybrid drive cycloidal motor for humanoid robot joint motors, solving the current problems.

[0014] To achieve the above objectives, the present invention provides the following technical solution: an electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor, comprising a motor rotor, an inner rotor connected to the motor rotor via a spline, inner needle teeth evenly distributed on the circumference of the inner rotor, an outer rotor disposed on one side of the inner needle teeth, an oil cavity surrounding the surface of the inner needle teeth and the inner contour of the outer rotor, an outer needle tooth disposed on one side of the outer rotor, an intermediate housing disposed on one side of the outer needle tooth, a low-pressure oil cavity surrounding the outer contour of the outer rotor, the surface of the outer needle teeth and the inner diameter of the intermediate housing, and a motor stator silicon steel sheet embedded in the intermediate housing, the upper end of the motor stator silicon steel sheet being wound with a fractional slot concentrated winding;

[0015] A left end cover is provided on one side of the motor rotor. An annular groove is provided on the left end cover. An adapter is embedded inside the left end cover. A rolling bearing is embedded between the left end cover and the motor rotor. A fixed baffle is provided on the left end of the left end cover and the rolling bearing.

[0016] The motor rotor is connected to a distribution plate via a keyway. A radial control groove is provided on the upper end of the distribution plate. Several sets of radial control grooves are provided. The intermediate housing is connected to the right end cover. A rolling bearing is embedded between the right end cover and the motor rotor.

[0017] In some embodiments, the inner needle teeth are provided in several groups and are in contact with the inner contour of the outer rotor.

[0018] In some embodiments, the outer rotor performs cycloidal motion, thereby driving the inner rotor and inner needle teeth to rotate. The inner rotor transmits the motion to the motor rotor to achieve concentric rotation of the motor rotor.

[0019] In some embodiments, the intermediate housing has an opening at a corresponding position, through which the fractional slot concentrated winding power line is led out.

[0020] In some embodiments, a permanent magnet is embedded at the upper end of the outer rotor, and the N and S poles of the permanent magnet are alternately distributed along the circumferential direction.

[0021] In some embodiments, a magnetic isolation bridge is embedded at the upper end of the outer rotor, and the magnetic isolation bridge is located between two adjacent permanent magnets.

[0022] In some embodiments, the outer rotor's outer profile at the motor end is smaller than that at the hydraulic end.

[0023] In some embodiments, the upper end of the left end cap is provided with an oil inlet and an oil outlet, and the oil inlet and oil outlet are connected to an annular groove.

[0024] In some embodiments, the right end cover has an oil outlet at its right end, which is connected to the gap between the stator and rotor.

[0025] In some embodiments, the adapter is provided with an oil inlet and an oil return hole, and the oil inlet and oil return holes are provided in several groups and are evenly distributed along the circumference.

[0026] In some embodiments, the stator silicon steel sheet and the outer rotor form a stator-rotor gap between the outer contour of the motor end, and the stator-rotor gap is connected in series with the low-pressure oil chamber in the axial direction.

[0027] In some embodiments, a rolling bearing is embedded between the left end cover and the motor rotor, and a rolling bearing is embedded between the right end cover and the motor rotor.

[0028] Compared with the prior art, the present invention provides an electro-hydraulic hybrid drive cycloidal motor for joint motors of humanoid robots, which has the following beneficial effects:

[0029] This invention relates to a cycloidal motor for joint motors in humanoid robots, employing a novel permanent magnet brushless DC motor (BLDC) topology—a cycloidal pair structure permanent magnet composite motor. It transforms the traditional stator-rotor relative circular motion pair into a cycloidal pair, generating a planetary motion trajectory for the rotor (consistent with the rotor trajectory of the internal cycloidal hydraulic motor), thus integrating hydraulic and electromagnetic energy. The internal cycloidal hydraulic motor and the BLDC are connected in series axially, with the BLDC using a cycloidal pair structure. The hydraulic motor and BLDC are coaxially integrated, achieving the superposition of hydraulic torque and electromagnetic torque. The total torque is output through a splined shaft.

[0030] The system employs a combined oil-electric cooling technology, where the working medium of the hydraulic system also serves as the cooling medium for the motor. Oil from the high- and low-pressure chambers of the hydraulic system flows directly into the stator tooth gap and the stator-rotor gap to cool the motor. This combined oil-electric cooling technology eliminates the need for a separate cooling system, significantly reducing system weight.

[0031] The hydraulic component of this application provides high torque, which is 3-5 times higher than that of traditional motors. The cycloidal pair structure permanent magnet composite motor provides torque compensation, resulting in a leap in power density and an overall torque density increase of over 200%. This application adopts a cycloidal pair structure, and the permanent magnet composite motor has its own reduction ratio, eliminating the need for a separate integrated reducer, which helps to reduce system size and weight. The use of a motor can compensate for the low bandwidth of hydraulic systems, and the high responsiveness (millisecond level) of the motor compensates for the delay of the hydraulic system, increasing the overall bandwidth to twice that of a pure hydraulic system. It is suitable for sensorless control technology.

[0032] Furthermore, this application utilizes the natural geometric salient pole characteristics of the cycloidal pair, combined with the back electromotive force of the motor, to achieve high-precision rotor position detection, eliminating the need for an encoder; it enhances heat dissipation efficiency, with a comprehensive heat dissipation capacity of 1kW / kg, controlling the temperature rise of key motor components, such as permanent magnets, below 60K, extending lifespan by 3 times, and meeting the high continuous torque requirements of humanoid robots; the overall integrated design, with an integrated oil cooling system, significantly reduces system size and weight compared to air-cooled solutions, making it more suitable for compact joint spaces. Attached Figure Description

[0033] Figure 1 This is a schematic diagram (cross-sectional view) of the electro-hydraulic hybrid drive cycloidal motor structure of the present invention.

[0034] Figure 2 This is a schematic diagram of the cross-section A1-A2 of the electro-hydraulic hybrid drive cycloidal motor of the present invention;

[0035] Figure 3 This is a schematic diagram of the cross-section B1-B2 of the electro-hydraulic hybrid drive cycloidal motor of the present invention;

[0036] Figure 4 This is a schematic diagram of the adapter structure of the present invention;

[0037] Figure 5 This is a schematic diagram of the distribution disk structure of the present invention.

[0038] In the diagram: 1. Motor rotor; 2. Inner rotor; 3. Inner pin teeth; 4. Outer rotor; 5. Oil chamber; 6. Permanent magnet; 7. Magnetic bridge; 8. Outer pin teeth; 9. Intermediate housing; 9a. Opening; 10. Low-pressure oil chamber; 11. Stator silicon steel sheet; 12. Fractional slot concentrated winding; 13. Left end cover; 13a. Left end cover oil inlet; 13b. Left end cover oil outlet; 14. Annular groove; 15. Adapter; 16. Left end rolling bearing; 17. External oil inlet; 18. Fixed baffle; 19. Distribution plate; 20. Radial control groove; 21. Right end cover; 21a. Right end cover oil outlet; 22. Right end rolling bearing; 23. External oil outlet; 24. Stator-rotor clearance; Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] Please see Figure 1-5 In this embodiment: an electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor includes a motor rotor 1, an inner rotor 2 connected to the motor rotor 1 via a spline, inner needle teeth 3 evenly distributed on the circumference of the inner rotor 2, an outer rotor 4 disposed on one side of the inner needle teeth 3, an oil cavity 5 surrounding the surface of the inner needle teeth 3 and the inner contour of the outer rotor 4, an outer needle tooth 8 disposed on one side of the outer rotor 4, an intermediate shell 9 disposed on one side of the outer needle tooth 8, and a low-pressure oil cavity 10 surrounding the outer contour of the outer rotor 4, the surface of the outer needle tooth 8 and the inner diameter of the intermediate shell 9.

[0042] In order to further increase the torque and dynamic response speed of the central shaft hydraulic cycloidal motor, a motor stator silicon steel sheet 11 is embedded in the intermediate housing 9, and a fractional slot concentrated winding 12 is wound on the upper end of the motor stator silicon steel sheet 11.

[0043] A left end cover 13 is provided on one side of the motor rotor 1. An annular groove 14 is provided on the left end cover 13. An adapter 15 is embedded inside the left end cover 13. A left end rolling bearing 16 is embedded between the left end cover 13 and the motor rotor 1.

[0044] The motor rotor 1 is connected to the distribution plate 19 via a keyway. The upper end of the distribution plate 19 is provided with a radial control groove 20. Several sets of radial control grooves 20 are provided. The middle housing 9 is connected to the right end cover 21.

[0045] In this embodiment, the inner needle teeth 3 are provided in several sets and are in contact with the inner contour of the outer rotor 4;

[0046] The motor rotor 1 rotates concentrically, thereby driving the inner rotor 2 and the inner needle tooth 3 to rotate. The inner needle tooth 3 transmits the motion to the outer rotor 4 to realize the cycloidal motion of the outer rotor 4.

[0047] An opening 9a is provided at the corresponding position of the intermediate housing 9, and the power line of the fractional slot concentrated winding 12 is led out through the opening 9a;

[0048] A permanent magnet 6 is embedded in the outer rotor 4, and the N and S poles of the permanent magnet 6 are alternately distributed along the circumferential direction;

[0049] The outer rotor 4 has a smaller outer contour dimension at the motor end than at the hydraulic end, so as to avoid rubbing against the teeth of the silicon steel sheet 11 of the motor stator;

[0050] The upper end of the left end cover 13 is provided with a left end cover oil inlet 13a and a left end cover oil outlet 13b, which are connected to the annular groove 14.

[0051] The adapter 15 is provided with an oil inlet hole 15a and an oil return hole 15b. Several sets of oil inlet holes 15a and oil return holes 15b are provided and are evenly distributed along the circumference.

[0052] The stator silicon steel sheet 11 and the outer rotor 4 form a stator-rotor gap 24 between their outer contours at the motor end.

[0053] The right end cover 21 has an oil outlet 21a on the right side. The oil outlet 21a is connected to the stator-rotor gap 24. The stator-rotor gap 24 is connected in series with the low-pressure oil chamber 10 in the axial direction. The low-pressure oil chamber 10 is connected to the oil outlet 13b on the left end cover 13.

[0054] To further improve torque and reduce magnetic leakage between permanent magnets 6, magnetic isolation bridges 7 are embedded between adjacent permanent magnets on the outer rotor 4.

[0055] To ensure precise centering and maintain the air gap between the stator and rotor, and to reduce friction and energy loss, a rolling bearing 16 is added between the motor rotor 1 and the left end cover 13, and a rolling bearing 22 is added between the motor rotor 1 and the right end cover 21.

[0056] The working principle and usage process of this invention are as follows: By supplying power to the fractional-slot concentrated winding 12, the outer rotor 4 can achieve cycloidal motion (rotation + revolution). The outer rotor 4 transmits the motion to the inner needle teeth 3, and the inner needle teeth 3 and the inner rotor 2 rotate together. The inner rotor 2 drives the motor rotor 1 to rotate concentrically through the spline shaft. While the outer rotor 4 is performing cycloidal motion, hydraulic oil flows into the external oil inlet 17, flows into the annular groove 14 through the oil inlet 13a of the left end cover, and then enters the oil inlet hole 15a in the adapter 15. The oil inlet hole 15a is misaligned with the radial control groove 20 in the distribution plate 19. The hydraulic oil flows into the oil chamber 5 through the overlapping part of the two holes. The pressure of the high-pressure chamber in the oil chamber 5 acts on the inner needle teeth 3, generating a hydraulic torque that makes the inner rotor 2 rotate. The inner rotor 2 drives the motor rotor 1 to rotate concentrically through the spline shaft. The electromagnetic torque and hydraulic torque acting on the motor rotor 1 are linearly superimposed, achieving the effect of increasing torque. The oil outlet 15b in the adapter 15 and the radial control groove 20 in the distribution plate 19 are interlocked. The hydraulic oil in the low-pressure chamber of the oil chamber 5 flows into the annular groove 14 through the overlapping part of the two holes, and then flows into the low-pressure oil chamber 10 from the oil outlet 13b of the left end cover. After passing through the low-pressure oil chamber 10, it flows into the motor stator-rotor gap 24 to cool the motor. Finally, it flows out from the oil outlet 21a of the right end cover and the external oil outlet 23 to complete the oil circuit circulation.

[0057] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0058] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cycloidal motor for electro-hydraulic hybrid drive of a humanoid robot joint motor, comprising a motor rotor (1), wherein the motor rotor (1) is connected to an inner rotor (2) via a spline, wherein inner needle teeth (3) are evenly distributed on the circumference of the inner rotor (2), and an outer rotor (4) is provided on one side of the inner needle teeth (3), wherein an oil cavity (5) is provided around the surface of the inner needle teeth (3) and the inner contour of the outer rotor (4), wherein a permanent magnet (6) and a magnetic isolation bridge (7) are embedded inside the outer rotor (4), wherein an outer needle tooth (8) is provided on one side of the outer rotor (4), and an intermediate shell (9) is provided on one side of the outer needle tooth (8), wherein a low-pressure oil cavity (10) is provided around the outer contour of the outer rotor (4), the surface of the outer needle tooth (8), and the inner diameter of the intermediate shell (9), characterized in that: The intermediate housing (9) is embedded with a motor stator silicon steel sheet (11), and the upper end of the motor stator silicon steel sheet (11) is wound with a fractional slot concentrated winding (12). A left end cover (13) is provided on one side of the motor rotor (1). An annular groove (14) is provided on the upper part of the left end cover (13). An adapter (15) is embedded inside the left end cover (13). A left end rolling bearing (16) is embedded between the left end cover (13) and the motor rotor (1). The upper side of the left end cover (13) is connected to an external oil inlet (17). A fixed baffle (18) is provided on the left side of the left end rolling bearing (16) and the left end cover (13). The motor rotor (1) is connected to a distribution plate (19) via a keyway. A radial control groove (20) is provided on the upper end of the distribution plate (19). Several sets of radial control grooves (20) are provided. The intermediate housing (9) is connected to the right end cover (21). A right end rolling bearing (22) is embedded between the right end cover (21) and the motor rotor (1). The right end cover (21) is connected to the right external oil outlet (23).

2. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: The inner needle teeth (3) are provided in several sets and are in contact with the inner contour of the outer rotor (4).

3. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: The outer rotor (4) performs cycloidal motion, thereby driving the inner rotor (2) and inner needle teeth (3) to rotate. The inner rotor (2) transmits the motion to the motor rotor (1), driving the motor rotor (1) to rotate concentrically.

4. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: The intermediate housing (9) has an opening (9a) at the corresponding position, and the power line of the fractional slot concentrated winding (12) is led out through the opening (9a).

5. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: A permanent magnet (6) is embedded in the outer rotor (4), and the N and S poles of the permanent magnet (6) are alternately distributed along the circumferential direction.

6. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: A magnetic isolation bridge (7) is embedded in the outer rotor (4), and the magnetic isolation bridge (7) is located between two adjacent permanent magnets (6).

7. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: The stator silicon steel sheet (11) and the outer rotor (4) form a stator-rotor gap (24) between the outer contour of the motor end, and the stator-rotor gap (24) is connected in series with the low-pressure oil chamber (10) in the axial direction.

8. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: The left end cap (13) has an oil inlet (13a) and an oil outlet (13b) at its upper end, and the right end cap (21) has an oil outlet (21a) at its right end. The left end cap oil inlet (13a) is connected to the annular groove (14) and the external oil inlet (17). The left end cap oil outlet (13b) is connected to the low-pressure oil chamber (10) and the annular groove (14), and the right end cap oil outlet (21a) is connected to the stator-rotor gap (24) and the external oil outlet (23).

9. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: The adapter (15) is provided with an oil inlet hole (15a) and an oil return hole (15b), and the oil inlet hole (15a) and the oil return hole (15b) are provided in several groups and are evenly distributed along the circumference.

10. The electro-hydraulic hybrid drive cycloidal motor for a humanoid robot joint motor according to claim 1, characterized in that: A left-end rolling bearing (16) is embedded between the motor rotor (1) and the left end cover (13), and a right-end rolling bearing (22) is embedded between the motor rotor (1) and the right end cover (21).

Images