A two-degree-of-freedom spherical hydraulic motor for a robot joint

Abstract

The application belongs to the technical field of liquid pressure actuators, and particularly relates to a two-degree-of-freedom spherical hydraulic motor for a robot joint, which solves the technical problem of existing spherical hydraulic motors that need to rely on external shafts and multiple execution elements to achieve two degrees of freedom and exist positioning error accumulation, and comprises an output shaft, a spherical rotor, a motor upper cover, a motor lower cover, a double-fan-ring piston and a single-fan-ring piston. The motor upper cover and the motor lower cover are opposite to each other, and a spherical inner cavity is formed in the interior of the motor upper cover and the motor lower cover. The output shaft is fixedly connected with the spherical rotor through an expansion through hole. A first sealed working cavity adapted to the double-fan-ring piston and a second sealed working cavity adapted to the single-fan-ring piston are arranged in the stator body. The spherical rotor is fixedly connected with an up-down driving pin shaft, a left-right driving pin shaft and an anti-rotation pin shaft. The inner spherical surface of the double-fan-ring piston and the single-fan-ring piston is provided with a movable groove. The up-down driving pin shaft is in sliding fit with the movable groove of the double-fan-ring piston, and the left-right driving pin shaft and the anti-rotation pin shaft are in sliding fit with the movable groove of the single-fan-ring piston.

Description

Technical Field

[0001] This invention belongs to the technical field of liquid pressure actuators, and relates to spherical motors, specifically a two-degree-of-freedom spherical hydraulic motor for robot joints. Background Technology

[0002] Existing two-degree-of-freedom spherical hydraulic motors are mostly based on hinge connections, with the hinge portion designed as a spherical structure and the housing using an irregularly shaped adaptable structure. The relative rotation angle of the hinge is controlled by the flow of hydraulic oil. Combined with the axial rotation of the input shaft, the entire motor can achieve two degrees of freedom. However, this type of two-degree-of-freedom spherical hydraulic motor can only independently control one degree of freedom; the other degree of freedom requires an external rotating shaft input. Essentially, it still belongs to a scheme that achieves multi-degree-of-freedom motion through the coupling of two actuators. Furthermore, each degree of freedom requires individual positioning control, leading to a problem of accumulated positioning errors; the more degrees of freedom there are, the greater the overall positioning error. Summary of the Invention

[0003] To overcome the technical shortcomings of existing two-degree-of-freedom spherical hydraulic motors, which rely on external shafts and multiple actuators to achieve two degrees of freedom and suffer from the accumulation of positioning errors, this invention provides a two-degree-of-freedom spherical hydraulic motor for robot joints.

[0004] This invention provides a two-degree-of-freedom spherical hydraulic motor for robot joints, comprising an output shaft, a spherical rotor, a motor upper cover, a motor lower cover, a double-fan ring piston, and a single-fan ring piston. The motor upper cover and the motor lower cover are fixedly joined together to form a stator body, the interior of which is assembled to form a spherical cavity adapted to the spherical rotor. An expansion through hole communicating with the spherical cavity is opened on the motor upper cover. The output shaft passes through the expansion through hole and is fixedly connected to the spherical rotor. The expansion through hole is used to provide swing clearance space for the output shaft. The stator body also has a first sealed working cavity adapted to the double-fan ring piston and a second sealed working cavity adapted to the single-fan ring piston. The inner spherical surfaces of the double-fan ring piston and the single-fan ring piston are respectively fitted with the spherical surface of the spherical rotor, and the outer spherical surfaces are respectively... The piston is fitted against the inner walls of the first and second sealed working chambers. The double-fan ring piston is placed laterally in the first sealed working chamber and divides it into an independent upper and lower chamber. The single-fan ring piston is placed vertically in the second sealed working chamber and divides it into an independent left and right chamber. The upper, lower, left, and right chambers are respectively provided with oil ports for connecting hydraulic lines. The spherical rotor is fixedly connected with the upper and lower drive pins, left and right drive pins, and anti-rotation pins located radially on the spherical rotor. The inner spherical surfaces of the double-fan ring piston and the single-fan ring piston are all circumferentially grooved. The upper and lower drive pins slide in the grooves of the double-fan ring piston, while the left and right drive pins and the anti-rotation pins slide in the grooves of the single-fan ring piston.

[0005] Both the upper and lower motor covers are cylindrical in shape. The upper cover has an upper chamber at its bottom, and the lower cover has a lower chamber at its top. The upper and lower chambers, when joined together, form a spherical inner cavity, the wall of which fits against the outer wall of the spherical rotor. The expansion through-hole refers to a through-hole whose diameter gradually increases from the inside to the outside along its axial direction. The opening of the expansion through-hole, connecting to the spherical inner cavity, has a rounded corner to prevent the structure from becoming too thin. Driven by the spherical rotor, the output shaft can swing back and forth and rotate around the cylindrical axis of the upper motor cover. The expansion through-hole has a swing range greater than that of the output shaft. The first and second sealing working chambers are both located between the upper and lower motor covers. The spherical rotor has three pin holes and one threaded hole for connecting the output shaft. The three pin holes correspond to the fixed installation of the upper and lower drive pins, the left and right drive pins, and the anti-rotation pin, respectively. Alternatively, the output shaft and the spherical rotor can be designed as a single, integral structure. The anti-rotation pin is used to prevent axial rotation of the left and right drive pins between the spherical rotor and the single-sector ring piston.

[0006] The dual-sector ring piston is an irregularly shaped piston, its basic cross-sectional shape being formed by two sector rings integrally spliced ​​together. The included angle of the larger sector ring is greater than that of the smaller sector ring, and the smaller sector ring is located inside the larger sector ring. The dual-sector ring piston is designed with a segmented structure of two sector rings. This is primarily because the smaller sector ring has a limited included angle due to the constraint that the upper and lower covers of the motor must provide sufficient support area for the spherical rotor. The larger sector ring does not have this limitation and can therefore use a larger included angle to increase the force-bearing area, thereby improving the motor's output torque. The surface of the double-fan ring piston that contacts the spherical rotor is the inner spherical surface, and the surface opposite the inner spherical surface is the outer spherical surface. The inner spherical surface of the large fan ring that is not covered by the small fan ring is the middle spherical surface. When the double-fan ring piston moves in the first sealed working chamber, the double-fan ring piston and the spherical rotor cooperate to form a spherical pair. Its inner spherical surface is always adapted to the outer wall of the spherical rotor, and its outer spherical surface and middle spherical surface are always adapted to the cavity wall of the first sealed working chamber. The surfaces of the double-fan ring piston that contact the upper cavity and the lower cavity are a pair of parallel pressure-bearing end faces. The ends of the double-fan ring piston are all conical surfaces, and the cavity wall of the first sealed working chamber is adapted to the conical surfaces at the ends of the double-fan ring piston.

[0007] Similarly, the single-sector ring piston is an irregularly shaped piston, with its basic cross-sectional shape being a single sector ring. The surface of the single-sector ring piston that contacts the spherical rotor is the inner spherical surface, and the surface opposite the inner spherical surface is the outer spherical surface. When the single-sector ring piston moves in the second sealed working chamber, it forms a spherical pair with the spherical rotor. Its inner spherical surface always fits the outer wall of the spherical rotor, and its outer spherical surface always fits the cavity wall of the second sealed working chamber. The surfaces of the single-sector ring piston that contact the left and right cavities are a pair of parallel pressure-bearing end faces. The ends of the single-sector ring piston are all conical surfaces, and the cavity wall of the second sealed working chamber fits the conical surfaces at the ends of the single-sector ring piston.

[0008] In order for the motor described in this invention to rotate, all spherical surfaces of the same piston must be concentric, all conical surfaces must be coaxial, and the axis must pass through the center of the spheres. Compared with the cylindrical contact of moving parts widely used in existing solutions, spherical contact has a larger force-bearing area, lower stress under the same load, and higher fatigue strength. With fewer parts and higher system reliability, the failure time of critical components is longer, resulting in a longer overall component lifespan.

[0009] Let the absolute rectangular coordinate system of the spherical rotor be xyz, with the origin at the center of the rotor and the z-axis pointing vertically upwards. Initially, the output shaft axis lies on the z-axis, as do the axes of the upper and lower motor covers. The x and y axes lie on a plane perpendicular to the origin, with the positive x-axis pointing towards the first sealed working chamber. The y-axis is determined by the right-hand rule, combining the x and z axes. During normal operation, the single-sector ring piston rotates only around the z-axis; therefore, a relative rectangular coordinate system uvw is established with the single-sector ring piston as the reference. The relative rectangular coordinate system is bound to the single-sector ring piston, and its relative motion with the absolute rectangular coordinate system is only rotation around the z-axis, meaning the w-axis is collinear with the z-axis. For ease of calculation, after the single-sector ring piston rotates by an angle φ along the z-axis, the relative rectangular coordinate system becomes the absolute rectangular coordinate system xyz rotated by an angle φ around the z-axis.

[0010] As can be seen from the assembly relationship, in the spherical contact between the spherical rotor and the single-sector ring piston, the rotation of the u-axis is constrained by the combined action of the left and right drive pins and the anti-rotation pin; the rotation of the w-axis is constrained by the contact between the inner wall of the sliding groove of the single-sector ring piston and the left and right drive pins and the anti-rotation pin; and the rotation of the v-axis is controlled by the constraint relationship between the double-sector ring piston and the upper and lower drive pins. Therefore, when high-pressure oil alternately enters the cavities on both sides of the single-sector ring piston and the cavities on both sides of the double-sector ring piston, it is possible to control the rotation of the spherical rotor around the z-axis and v-axis within the designed stroke. For example, rotation around the z-axis alone (the single-sector ring piston makes the main movement, and the double-sector ring piston makes the auxiliary movement so that the rotation angle of the spherical rotor around the v-axis remains unchanged), rotation around the v-axis alone (the single-sector ring piston is stationary, and the double-sector ring piston moves), and a combination of the above two movements.

[0011] Preferably, an integrated hydraulic valve module is fixedly connected below the lower cover of the motor. Two sets of three-position four-way solenoid valves are installed within the integrated hydraulic valve module. The module also has a first return port, a second return port, and a main inlet port. The pressure ports of the two sets of three-position four-way solenoid valves are connected in parallel to the main inlet port. The return ports of the two sets of three-position four-way solenoid valves are respectively connected to the first return port and the second return port. The two working ports of one set of three-position four-way solenoid valves are connected to the oil ports of the upper and lower chambers respectively through internal pipelines. The two working ports of the other set of three-position four-way solenoid valves are connected to the oil ports of the left and right chambers respectively through internal pipelines. The main body of the integrated hydraulic valve module is cylindrical for ease of installation and use. Three planes are cut on the side of the cylindrical integrated hydraulic valve module, and these three planes are perpendicular to each other. The first return port, the second return port, and the main inlet port are located on one of these planes. The remaining two planes are parallel to each other. Two sets of three-position four-way solenoid valves are installed between these two planes. The oil seal of the three-position four-way solenoid valve is located on one plane, while the electromagnet and other components are installed on the other plane. The first return port, the second return port, and the main inlet are all standard hydraulic interfaces that can be connected to external standard fluid pipes. The two sets of three-position four-way solenoid valves control the first and second sealing working chambers respectively. The return ports of the two sets of three-position four-way solenoid valves are connected to the first and second return ports respectively, which is an independent return design for each degree of freedom control, eliminating the need for designing a check valve and control system that would increase the back pressure calculation work. Changing the oil flow state of the motor body (forward, reverse, closed) is accomplished by changing the relative position of the valve core of the three-position four-way solenoid valve. The three-position four-way solenoid valve is designed with a neutral position function. When the valve core is in the neutral position, the oil port is closed and the motor is self-locking; when the valve core is in the two positions, forward and reverse oil flow is achieved to their respective two output ports. The two sets of three-position four-way solenoid valves can also be replaced with three-position four-way proportional directional valves. Adjusting the displacement of the valve core off the midpoint can control the flow rate and pressure of the pressurized oil leading to the chamber.

[0012] Preferably, an actuator module is also fixedly connected below the integrated hydraulic valve module. The actuator module is electrically connected to the electromagnets of two sets of three-position four-way solenoid valves to control the movement of the valve core. The internal geometry and specific circuit board of the actuator module are not limited. The actuator module includes components such as a controller and a power supply module, which are designs well-known to those skilled in the art. The interface of the actuator module can be expanded, for example, designed as an electromagnet control interface, a sensor interface, and a measurement and control interface. The pins of the electromagnet interface connect to a proportional electromagnet or electromagnet to directly control the valve core; the sensor interface connects to a sensor module for collecting various types of information. The measurement and control interface consists of power supply positive and negative terminals, signal input / output, and signal ground, used to connect to a host computer to receive component status and issue control commands.

[0013] Preferably, the motor upper cover, motor lower cover, integrated hydraulic valve module, and driver module are fixedly connected by multiple through bolts and nuts. The motor upper cover, motor lower cover, integrated hydraulic valve module, and driver module have multiple circumferentially arranged through holes. The long bolts are inserted into these through holes to connect the motor upper cover, motor lower cover, integrated hydraulic valve module, and driver module together. Nuts are then used to secure the long bolts at both ends, achieving long bolt installation. In final use, the hydraulic motor described in this invention can be fixed to the frame by bolts.

[0014] Preferably, the bottom surface of the motor upper cover and the top surface of the motor lower cover are provided with multiple sets of matching locating pins and locating holes. This facilitates the quick installation of the motor upper cover and the motor lower cover, allowing the internal cavity to be assembled within the design tolerance requirements.

[0015] Preferably, a sealing groove is provided between the joint of the upper and lower motor covers, and sealing rings for the upper and lower covers are fitted into the sealing groove. This arrangement prevents leakage from the first and second sealing chambers, ensuring the normal operation of the hydraulic motor. This is well known to those skilled in the art.

[0016] Preferably, a rotor sealing ring is provided between the spherical inner cavity at the motor cover and the spherical rotor. This arrangement prevents leakage from the first and second sealing working chambers, ensuring the normal operation of the hydraulic motor.

[0017] Preferably, the up-and-down drive pins, left-and-right drive pins, and anti-rotation pins are coplanar. This arrangement is structurally sound; the coplanarity of the three components facilitates calculations during structural design and maximizes the stroke of the pins within their corresponding movable slots. Even if the three components are not coplanar, a two-degree-of-freedom spherical hydraulic motor can still be designed to solve technical problems.

[0018] Preferably, the motor upper cover, motor lower cover, and integrated hydraulic valve module are equipped with multiple flow channels. The specific arrangement of these flow channels is not limited; they can be arranged reasonably according to the actual structural size. The flow channels connect the oil ports of the upper, lower, left, and right chambers to the corresponding working ports of the three-position four-way solenoid valve. In addition, the flow channels in the integrated hydraulic valve module also connect the corresponding oil ports of the three-position four-way solenoid valve to the first return oil port, the second return oil port, and the main inlet oil port, thereby achieving connection with external oil circuits.

[0019] The technical solution provided by this invention has the following technical effects compared with the prior art:

[0020] The motor body controls two degrees of freedom through the cooperation of two pistons moving in different directions. Furthermore, the hydraulic transmission of the hydraulic motor described in this invention is smooth, and the absence of a reducer structure (harmonic reducer, planetary reducer) results in greater rigidity and faster response. It also avoids the accumulation of motion errors in multi-motor solutions, directly improving control accuracy. Regarding feedback adjustment, since there is only one measured object (the output shaft of the spherical hydraulic motor or the rotor ball), the accumulation of errors from multiple measured objects is avoided, indirectly improving control accuracy. Single-installation avoids the accumulation of installation errors associated with multiple single-degree-of-freedom motor combinations used in existing humanoid robots, indirectly improving control accuracy. Alternatively, under the same installation accuracy requirements, the parts using this invention have lower precision requirements and lower processing costs, or under the same processing accuracy, the overall positioning accuracy of this invention is higher.

[0021] This invention features a compact structure, making it suitable for applications with limited space. It avoids the structural redundancy, system bulkiness, low utilization of component material mechanical properties, and large installation volume caused by combining multiple actuators, while also preventing the integrated joint components from having a more complex shape. The highly integrated module reduces the workload of equipment design. Compared to existing spherical hydraulic motors, this invention does not rely on external mechanical transmission input; it achieves two degrees of freedom control purely through fluid transmission and electrical signals. This simplifies the complexity of R&D management (such as BOM statistics) and reduces management difficulty.

[0022] Calculations show that, for the same nominal spherical radius, the theoretical maximum torque of a hydraulic motor is three orders of magnitude higher than that of a permanent magnet spherical motor, and its torque on a single shaft is one order of magnitude higher than that of an articulated motor. Hydraulic components have high power density, enabling them to maintain high operating speeds while bearing heavy loads, such as in the heavy-duty handling of robots.

[0023] The control method of the hydraulic motor described in this invention is simple. Compared with the permanent magnet spherical motor which requires the control of the current of dozens of coils, this motor only needs to control two three-position four-way solenoid valves. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1This is a front view of a two-degree-of-freedom spherical hydraulic motor for a robot joint according to a certain embodiment of the present invention;

[0027] Figure 2 This is a three-dimensional diagram of a two-degree-of-freedom spherical hydraulic motor for a robot joint according to a certain embodiment of the present invention;

[0028] Figure 3 This is a cross-sectional view of a two-degree-of-freedom spherical hydraulic motor for a robot joint according to a certain embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the spherical rotor connecting the output shaft and different pins in a certain embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of the structure of the single sector piston in a certain embodiment of the present invention;

[0031] Figure 6 This is a first-view structural schematic diagram of the double-fan ring piston according to a certain embodiment of the present invention;

[0032] Figure 7 This is a second-view structural schematic diagram of the double-fan ring piston according to a certain embodiment of the present invention;

[0033] Figure 8 This is a schematic diagram of the structure of the motor cover in a certain embodiment of the present invention;

[0034] Figure 9 This is a schematic diagram of the structure of the motor lower cover in a certain embodiment of the present invention;

[0035] Figure 10 This is a schematic diagram of the structure of the spherical rotor combined with a single-fan ring piston and a double-fan ring piston in a certain embodiment of the present invention;

[0036] Figure 11 for Figure 10 Schematic diagram of the structure after removing the single-ring piston and the double-ring piston;

[0037] Figure 12 for Figure 10 Perspective view;

[0038] Figure 13 This is a first-view split diagram of the spherical rotor, motor upper cover, and motor lower cover according to a certain embodiment of the present invention;

[0039] Figure 14 This is a second-view split diagram of the spherical rotor, motor upper cover, and motor lower cover described in a certain embodiment of the present invention;

[0040] Figure 15 This is a perspective view of the integrated hydraulic valve module described in a certain embodiment of the present invention;

[0041] Figure 16 This is a cross-sectional view of the integrated hydraulic valve module described in a certain embodiment of the present invention;

[0042] Figure 17 This is a schematic diagram of the internal flow channel of the integrated hydraulic valve module according to a certain embodiment of the present invention;

[0043] Figure 18 This is a schematic diagram of the oil ports on the first and second sealing working chambers in a certain embodiment of the present invention;

[0044] Figure 19 This is an isometric sectional view of a two-degree-of-freedom spherical hydraulic motor for a robot joint according to a certain embodiment of the present invention;

[0045] Figure 20 This is a schematic diagram of the relative rectangular coordinate system of a two-degree-of-freedom spherical hydraulic motor for robot joints according to a certain embodiment of the present invention.

[0046] In the diagram: 1. Output shaft; 2. Spherical rotor; 3. Motor upper cover; 4. Motor lower cover; 5. Double-sector ring piston; 6. Single-sector ring piston; 7. Expansion through hole; 8. First sealing working chamber; 9. Second sealing working chamber; 10. Oil port; 11. Upper and lower drive pins; 12. Left and right drive pins; 13. Anti-rotation pin; 14. Movable groove; 15. Integrated hydraulic valve module; 16. Three-position four-way solenoid valve; 17. First oil return port; 18. Second oil return port; 19. Main oil inlet; 20. Driver module; 21. Long bolt; 22. Nut; 23. Locating pin; 24. Locating hole; 25. Sealing groove; 26. Upper and lower cover sealing rings; 27. Rotor sealing ring; 28. Flow channel; 29. ​​Oil seal; 30. Electromagnet. Detailed Implementation

[0047] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0048] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0049] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0050] The following is in conjunction with the appendix Figures 1 to 20 Specific embodiments of the present invention will be described in detail below.

[0051] In one embodiment, such as Figure 1 As shown, a two-degree-of-freedom spherical hydraulic motor for robot joints is disclosed, including an output shaft 1, a spherical rotor 2, a motor upper cover 3, a motor lower cover 4, a double-fan ring piston 5, and a single-fan ring piston 6. The motor upper cover 3 and the motor lower cover 4 are fixedly joined together to form a stator body, and their internal components are combined to form a spherical inner cavity adapted to the spherical rotor 2. An expansion through hole 7 is opened on the motor upper cover 3 to communicate with the spherical inner cavity. The output shaft 1 passes through the expansion through hole 7 and is fixedly connected to the spherical rotor. The expansion through hole 7 is used to provide swing clearance space for the output shaft 1. The stator body is also provided with a first sealed working cavity 8 adapted to the double-fan ring piston 5 and a second sealed working cavity 9 adapted to the single-fan ring piston 6. The inner spherical surfaces of the double-fan ring piston 5 and the single-fan ring piston 6 are respectively fitted with the spherical surface of the spherical rotor 2, and the outer spherical surfaces are respectively fitted with the first sealed working cavity 9. The inner walls of the working chamber 8 and the second sealed working chamber 9 are fitted together; the double-fan ring piston 5 is placed laterally in the first sealed working chamber 8 and is divided into an independent upper chamber and a lower chamber, and the single-fan ring piston 6 is placed vertically in the second sealed working chamber 9 and is divided into an independent left chamber and a right chamber. The upper chamber, lower chamber, left chamber and right chamber are respectively provided with oil ports 10 for connecting hydraulic lines; the spherical rotor 2 is fixedly connected with the upper and lower drive pins 11, the left and right drive pins 12 and the anti-rotation pins 13 located radially on the spherical rotor 2, and the inner spherical surfaces of the double-fan ring piston 5 and the single-fan ring piston 6 are both provided with movable grooves 14 along the circumference. The upper and lower drive pins 11 are slidably engaged with the movable grooves 14 of the double-fan ring piston 5, and the left and right drive pins 12 and the anti-rotation pins 13 are simultaneously slidably engaged with the movable grooves 14 of the single-fan ring piston 6.

[0052] Both the upper motor cover 3 and the lower motor cover 4 are cylindrical in shape. The upper motor cover 3 has an upper chamber at its bottom, and the lower motor cover 4 has a lower chamber at its top. The upper and lower chambers are joined together to form a spherical inner cavity, the wall of which fits against the outer wall of the spherical rotor 2. The expansion through-hole 7 refers to a through-hole whose diameter gradually increases from the inside to the outside along the axial direction. The opening of the expansion through-hole 7, which connects to the spherical inner cavity, has a transition rounded corner to prevent the structure from being too thin. Driven by the spherical rotor 2, the output shaft 1 can swing back and forth and rotate around the cylindrical axis of the upper motor cover 3. The expansion through-hole 7 is larger than the swing range of the output shaft 1. The first sealing working chamber 8 and the second sealing working chamber 9 are both located between the upper motor cover 3 and the lower motor cover 4. The spherical rotor 2 has three pin holes and one threaded hole for connecting the output shaft 1. The three pin holes are respectively used to fix and install the upper and lower drive pins 11, the left and right drive pins 12, and the anti-rotation pin 13. Specifically, the output shaft 1 and the spherical rotor 2 can also be designed as an integral structure. The anti-rotation pin 13 is used to prevent axial rotation of the left and right drive pins 12 between the spherical rotor 2 and the single-sector ring piston 6.

[0053] The dual-fan-ring piston 5 is an irregularly shaped piston, its basic cross-sectional shape being formed by two fan-rings integrally spliced ​​together. The included angle of the larger fan-ring is greater than that of the smaller fan-ring, and the smaller fan-ring is located inside the larger fan-ring. The dual-fan-ring piston 5 is designed with a segmented structure of two fan-rings, mainly considering that the included angle of the smaller fan-ring is limited under the constraint that the upper and lower covers of the motor must provide sufficient support area for the spherical rotor 2. The larger fan-ring, without this limitation, can use a larger included angle to increase the force-bearing area, thereby improving the output torque of the motor. The surface of the double-fan ring piston 5 that contacts the spherical rotor 2 is the inner spherical surface, and the surface opposite to the inner spherical surface is the outer spherical surface. The inner spherical surface of the large fan ring that is not covered by the small fan ring is the middle spherical surface. When the double-fan ring piston 5 moves in the first sealed working chamber 8, the double-fan ring piston 5 and the spherical rotor 2 cooperate to form a spherical pair. Its inner spherical surface is always adapted to the outer wall of the spherical rotor 2, and its outer spherical surface and middle spherical surface are always adapted to the cavity wall of the first sealed working chamber 8. The surfaces of the double-fan ring piston 5 that contact the upper cavity and the lower cavity are a pair of parallel pressure-bearing end faces. The ends of the double-fan ring piston 5 are all conical surfaces, and the cavity wall of the first sealed working chamber 8 is adapted to the conical surfaces at the ends of the double-fan ring piston 5.

[0054] Similarly, the single-fan ring piston 6 is an irregularly shaped piston, with its basic cross-sectional shape being a single fan ring. The surface of the single-fan ring piston 6 that contacts the spherical rotor 2 is the inner spherical surface, and the surface opposite to the inner spherical surface is the outer spherical surface. When the single-fan ring piston 6 moves in the second sealed working chamber 9, the single-fan ring piston 6 and the spherical rotor 2 cooperate to form a spherical pair. Its inner spherical surface is always adapted to the outer wall of the spherical rotor 2, and its outer spherical surface is always adapted to the cavity wall of the second sealed working chamber 9. The surfaces of the single-fan ring piston 6 that contact the left and right cavities are a pair of parallel pressure-bearing end faces. The ends of the single-fan ring piston 6 are all conical surfaces, and the cavity wall of the second sealed working chamber 9 is adapted to the conical surfaces at the ends of the single-fan ring piston 6.

[0055] In order for the motor described in this invention to rotate, all spherical surfaces of the same piston must be concentric, all conical surfaces must be coaxial, and the axis must pass through the center of the spheres. Compared with the cylindrical contact of moving parts widely used in existing solutions, spherical contact has a larger force-bearing area, lower stress under the same load, and higher fatigue strength. With fewer parts and higher system reliability, the failure time of critical components is longer, resulting in a longer overall component lifespan.

[0056] Let the absolute rectangular coordinate system of the spherical rotor 2 be xyz, with the origin of the absolute rectangular coordinate system located at the center of the spherical rotor 2. The z-axis is vertically upward. In the initial state, the axis of the output shaft 1 is located on the z-axis, and the axes of the upper motor cover 3 and the lower motor cover 4 are also located on the z-axis. The x-axis and y-axis lie on the plane perpendicular to the origin, with the positive direction of the x-axis pointing towards the first sealed working chamber 8. The y-axis is determined by the right-hand rule in combination with the x-axis and z-axis. During normal operation, the single-sector ring piston 6 only rotates around the z-axis. Therefore, a relative rectangular coordinate system uvw is established with the single-sector ring piston 6 as the reference. The relative rectangular coordinate system is bound to the single-sector ring piston 6, and its relative motion with the absolute rectangular coordinate system is only the rotation around the z-axis, i.e., the w-axis is collinear with the z-axis. For ease of calculation, when the single-sector ring piston 6 rotates by an angle φ along the z-axis, the relative rectangular coordinate system is the coordinate system after the absolute rectangular coordinate system xyz has rotated by an angle φ around the z-axis.

[0057] As can be seen from the assembly relationship, in the spherical contact between the spherical rotor 2 and the single-fan ring piston 6, the rotation of the u-axis is constrained by the combined action of the left and right drive pins 12 and the anti-rotation pin 13. The rotation of the w-axis is constrained by the contact between the inner wall of the movable groove 14 of the single-fan ring piston 6 and the left and right drive pins 12 and the anti-rotation pin 13. The rotation of the v-axis is controlled by the constraint relationship between the double-fan ring piston 5 and the upper and lower drive pins 11. Therefore, when high-pressure oil alternately enters the cavities on both sides of the single-fan ring piston 6 and the cavities on both sides of the double-fan ring piston 5, the spherical rotor 2 can be controlled to rotate around the z-axis and v-axis within the designed stroke. For example, rotation around the z-axis alone (the single-fan ring piston 6 makes the main movement, and the double-fan ring piston 5 makes the auxiliary movement so that the rotation angle of the spherical rotor 2 around the v-axis remains unchanged), rotation around the v-axis alone (the single-fan ring piston 6 is stationary, and the double-fan ring piston 5 moves), and a combination of the above two movements.

[0058] Based on the above embodiments, in a further preferred embodiment, an integrated hydraulic valve module 15 is fixedly connected below the lower cover 4 of the motor. Two sets of three-position four-way solenoid valves 16 are installed within the integrated hydraulic valve module 15. The integrated hydraulic valve module 15 is also provided with a first return port 17, a second return port 18, and a total inlet port 19. The pressure ports of the two sets of three-position four-way solenoid valves 16 are connected in parallel to the total inlet port 19. The return ports 10 of the two sets of three-position four-way solenoid valves 16 are respectively connected to the first return port 17 and the second return port 18. The two working ports of one set of three-position four-way solenoid valves 16 are respectively connected to the oil ports 10 of the upper and lower cavities via internal pipelines. The two working ports of the other set of three-position four-way solenoid valves 16 are respectively connected to the oil ports 10 of the left and right cavities via internal pipelines. The main body of the integrated hydraulic valve module 15 is cylindrical for ease of installation and use. Three planes are opened on the side of the cylindrical integrated hydraulic valve module 15, and these three planes are perpendicular to each other. The first return port 17, the second return port 18, and the main inlet port 19 are located on one of the planes. The remaining two planes are parallel to each other, and two sets of three-position four-way solenoid valves 16 are installed between these two planes. The oil seal 29 of the three-position four-way solenoid valve 16 is located on one plane, and components such as the electromagnet 30 are installed on the other plane. The first return port 17, the second return port 18, and the main inlet port 19 are all standard hydraulic interfaces that can be connected to external standard fluid pipes. The two sets of three-position four-way solenoid valves 16 control the first sealing working chamber 8 and the second sealing working chamber 9, respectively. The return ports 10 of the two sets of three-position four-way solenoid valves 16 are connected to the first return port 17 and the second return port 18, respectively. This design provides independent return ports for each degree of freedom, eliminating the need for designing check valves and control systems that would increase the calculation of back pressure. Changing the oil flow state of the motor body (forward, reverse, closed) is accomplished by changing the relative position of the valve cores of the three-position four-way solenoid valves 16. The three-position four-way solenoid valve 16 is designed with a neutral position function. When the valve core is in the neutral position, the oil port 10 is closed and the motor is self-locking. When the valve core is in either of the two positions, it enables forward and reverse oil flow to its respective two output ports. The two sets of three-position four-way solenoid valves 16 can also be replaced with three-position four-way proportional directional valves. Adjusting the displacement of the valve core off the midpoint can control the flow rate and pressure of the pressurized oil flowing into the chamber.

[0059] Based on the above embodiments, in a further preferred embodiment, an actuator module 20 is fixedly connected below the integrated hydraulic valve module 15. The actuator module 20 is electrically connected to the electromagnets 30 of the two sets of three-position four-way solenoid valves 16 for controlling the movement of the valve core. The internal geometry of the actuator module 20 and the specific circuit board are not limited. The actuator module 20 includes components such as a controller and a power supply module, which are designs well known to those skilled in the art. The interface of the actuator module 20 can be expanded, for example, designed as an electromagnet 30 control interface, a sensor interface, and a measurement and control interface. The pins of the electromagnet 30 interface are connected to the proportional electromagnet 30 or electromagnet 30 to directly control the valve core; the sensor interface is connected to the sensor module for collecting various types of information. The measurement and control interface consists of power supply positive and negative terminals, signal input / output, and signal ground, and is used to connect to a host computer to receive component status and issue control commands.

[0060] Based on the above embodiments, in a further preferred embodiment, the motor upper cover 3, motor lower cover 4, integrated hydraulic valve module 15, and driver module 20 are fixedly connected by multiple through bolts and nuts 22. The motor upper cover 3, motor lower cover 4, integrated hydraulic valve module 15, and driver module 20 have multiple circumferentially arranged through holes. The long bolts are inserted into these through holes, connecting the motor upper cover 3, motor lower cover 4, integrated hydraulic valve module 15, and driver module 20 together. Nuts 22 are then used to fix the long bolts at both ends, achieving long bolt installation. In final use, the hydraulic motor described in this invention can be fixed to the frame by bolts.

[0061] Based on the above embodiments, in a further preferred embodiment, multiple sets of matching positioning pins 23 and positioning holes 24 are provided on the bottom surface of the upper motor cover 3 and the top surface of the lower motor cover 4. This facilitates the quick installation of the upper motor cover 3 and the lower motor cover 4, so that the internal cavity can be assembled to meet the design requirements in terms of tolerance.

[0062] Based on the above embodiments, in a further preferred embodiment, a sealing groove 25 is provided between the joint of the upper motor cover 3 and the lower motor cover 4, and upper and lower cover sealing rings 26 are fitted in the sealing groove 25. This arrangement can prevent leakage from the first sealing working chamber 8 and the second sealing working chamber 9, ensuring that the hydraulic motor can work normally. This is well known to those skilled in the art.

[0063] Based on the above embodiments, in a further preferred embodiment, a rotor sealing ring 27 is provided between the spherical inner cavity at the motor cover 3 and the spherical rotor 2. This arrangement can prevent leakage from the first sealing working chamber 8 and the second sealing working chamber 9, ensuring that the hydraulic motor can work normally.

[0064] Based on the above embodiments, in a further preferred embodiment, the up-down drive pin 11, the left-right drive pin 12, and the anti-rotation pin 13 are coplanar. This arrangement is reasonable; the coplanarity of the three components facilitates calculations during structural design and maximizes the stroke of the pins in the corresponding movable grooves 14. Even if the three components are not coplanar, a two-degree-of-freedom spherical hydraulic motor that solves the technical problem can still be designed.

[0065] Based on the above embodiments, in a further preferred embodiment, multiple flow channels are provided in the motor upper cover 3, the motor lower cover 4, and the integrated hydraulic valve module 15. The specific arrangement of the flow channels is not limited; they can be arranged reasonably according to the actual structural size. The flow channels are used to connect the oil ports 10 of the upper cavity, lower cavity, left cavity, and right cavity to the working ports of the three-position four-way solenoid valve 16. In addition, the flow channels in the integrated hydraulic valve module 15 are also used to connect the corresponding oil ports 10 of the three-position four-way solenoid valve 16 to the first return oil port 17, the second return oil port 18, and the main oil inlet port 19, respectively, thereby achieving connection with external oil circuits.

[0066] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A two-degree-of-freedom spherical hydraulic motor for robot joints, characterized in that, The stator body includes an output shaft (1), a spherical rotor (2), a motor top cover (3), a motor bottom cover (4), a double-fan ring piston (5), and a single-fan ring piston (6). The motor top cover (3) and the motor bottom cover (4) are fixed together to form the stator body. The internal assembly forms a spherical cavity that is adapted to the spherical rotor (2). An expansion through hole (7) communicating with the spherical cavity is opened on the motor top cover (3). The output shaft (1) passes through the expansion through hole (7) and is fixedly connected to the ball head rotor. The expansion through hole (7) is used to provide swing clearance space for the output shaft (1). The stator body is also provided with a first sealing working cavity (8) adapted to the double-fan ring piston (5) and a second sealing working cavity (9) adapted to the single-fan ring piston (6). The inner spherical surfaces of the double-fan ring piston (5) and the single-fan ring piston (6) are respectively attached to the spherical surface of the spherical rotor (2), and the outer spherical surfaces are respectively attached to the first sealing working cavity (8) and the second sealing working cavity (9). The inner wall of the cavity (9) is fitted together; the double-fan ring piston (5) is placed horizontally in the first sealed working cavity (8) and it is divided into an independent upper cavity and a lower cavity; the single-fan ring piston (6) is placed vertically in the second sealed working cavity (9) and it is divided into an independent left cavity and a right cavity; the upper cavity, the lower cavity, the left cavity and the right cavity are respectively provided with oil ports (10) for connecting hydraulic pipelines; the spherical rotor (2) is fixedly connected with the upper and lower drive pins (11), the left and right drive pins (12) and the anti-rotation pins (13) located in the radial direction of the spherical rotor (2); the inner spherical surfaces of the double-fan ring piston (5) and the single-fan ring piston (6) are all provided with movable grooves (14) along the circumference; the upper and lower drive pins (11) are slidably engaged with the movable grooves (14) of the double-fan ring piston (5); the left and right drive pins (12) and the anti-rotation pins (13) are simultaneously slidably engaged with the movable grooves (14) of the single-fan ring piston (6).

2. A two-degree-of-freedom spherical hydraulic motor for robot joints according to claim 1, characterized in that, An integrated hydraulic valve module (15) is fixedly connected below the motor cover (4). Two sets of three-position four-way solenoid valves (16) are installed in the integrated hydraulic valve module (15). The integrated hydraulic valve module (15) is also provided with a first return port (17), a second return port (18) and a total inlet port (19). The pressure ports of the two sets of three-position four-way solenoid valves (16) are connected in parallel to the total inlet port (19). The return ports of the two sets of three-position four-way solenoid valves (16) are connected to the first return port (17) and the second return port (18) respectively. The two working ports of one set of three-position four-way solenoid valves (16) are connected to the oil ports (10) of the upper cavity and the lower cavity respectively through the built-in pipeline. The two working ports of the other set of three-position four-way solenoid valves (16) are connected to the oil ports (10) of the left cavity and the right cavity respectively through the built-in pipeline.

3. A two-degree-of-freedom spherical hydraulic motor for robot joints according to claim 2, characterized in that, Below the integrated hydraulic valve module (15), there is also a fixed drive module (20). The drive module (20) is electrically connected to the electromagnets (30) of the two sets of three-position four-way solenoid valves (16) to control the movement of the valve core.

4. A two-degree-of-freedom spherical hydraulic motor for robot joints according to claim 3, characterized in that, The motor top cover (3), motor bottom cover (4), integrated hydraulic valve module (15) and driver module (20) are fixedly connected by multiple long bolts (21) and nuts (22) that run through the motor.

5. A two-degree-of-freedom spherical hydraulic motor for a robot joint according to claim 4, characterized in that, Multiple sets of matching positioning pins (23) and positioning holes (24) are also provided on the bottom surface of the motor upper cover (3) and the top surface of the motor lower cover (4).

6. A two-degree-of-freedom spherical hydraulic motor for a robot joint according to any one of claims 1 to 5, characterized in that, A sealing groove (25) is provided between the joint of the upper cover (3) and the lower cover (4) of the motor, and a sealing ring (26) of the upper and lower covers is installed in the sealing groove (25).

7. A two-degree-of-freedom spherical hydraulic motor for a robot joint according to claim 6, characterized in that, A rotor sealing ring (27) is provided between the spherical inner cavity of the motor cover (3) and the spherical rotor (2).

8. A two-degree-of-freedom spherical hydraulic motor for a robot joint according to claim 7, characterized in that, The up-down drive pin (11), the left-right drive pin (12), and the anti-rotation pin (13) are coplanar.

9. A two-degree-of-freedom spherical hydraulic motor for a robot joint according to claim 8, characterized in that, Multiple flow channels (28) are provided in the motor top cover (3), motor bottom cover (4) and integrated hydraulic valve module (15).

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