A two-degree-of-freedom hydraulic joint

Abstract

This invention provides a two-degree-of-freedom hydraulic joint, belonging to the field of hydraulic drive and servo control. The inner rotor has a sphere in the center, with an output shaft at one end and a swing blade at the other. The outer rotor has a hollow interior, and the swing blade of the inner rotor is nested within the outer rotor cavity, dividing the outer rotor cavity into two chambers, thus enabling the swing of the inner rotor blade and achieving the first degree of freedom (rotation). The combined inner and outer rotors are mounted on the inner spherical surface of the stator base, forming two sealed chambers with the hollow portion of the stator base, allowing the outer rotor to drive the inner rotor together to achieve the second degree of freedom (rotation). This invention enables two independent degrees of freedom in the mechanical joint, significantly reducing the total mass of the robotic arm and simplifying the traditional complex robotic arm transmission chain. Hydraulic drive can achieve greater driving force compared to electric drive, achieving both simplicity and efficiency.

Description

Technical Field

[0001] This invention relates to a two-degree-of-freedom hydraulic joint, belonging to the field of hydraulic drive and servo control. Background Technology

[0002] Currently, robots can be classified into four types according to their structure: Cartesian coordinate, cylindrical coordinate, spherical coordinate, and articulated coordinate. Among them, articulated coordinate robots have advantages such as flexible movement, large workspace, and small footprint. However, most rotary joints have only one degree of rotational freedom. Two-degree-of-freedom joints can reduce the number of joints in a robot and significantly improve rigidity. The coincidence of the centers of the two rotational movements ensures motion accuracy and makes the robot structure more compact.

[0003] In traditional robotic arms, each joint is driven by a motor. Since motors account for a large proportion of the weight of the robotic arm joints, multiple motors account for most of the weight of the cantilever section of the robotic arm. Therefore, in the above situation, using a new motor to enable a single motor to control the movement of two joints can significantly reduce the weight of the cantilever section of the robotic arm. This is a way to achieve a more compact structure and a high load-to-weight ratio. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the prior art, and to provide a two-degree-of-freedom swing hydraulic motor with an outer rotor and an inner rotor nested together, directly driven by hydraulic pressure, capable of two independent degrees of freedom of rotation, and with a simple and compact structure.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A two-degree-of-freedom hydraulic joint, the two-degree-of-freedom hydraulic joint comprising an inner rotor, an outer rotor, a sliding bearing, a stator base, and a stator cover;

[0007] The inner rotor has a sphere in the middle, one end of which is the output shaft of the inner rotor, which is also the output shaft of the two-degree-of-freedom hydraulic joint, and the other end is an inner rotor blade with a rectangular cross section. The inner rotor blade has rotor blade sealing grooves on both sides.

[0008] The outer rotor body is hemispherical, with the blade slots inside the outer rotor nested with the blades of the inner rotor. The center of the outer rotor's blades coincides with the center of the inner rotor's blades. The outer rotor has two parallel sides, which are fan-shaped with holes cut at the center of the fan-shaped sides to accommodate sliding bearings. The fan-shaped sides are provided with oil distribution grooves, and the oil distribution grooves are provided with outer rotor oil holes. The bottom of the oil distribution grooves is provided with oil distribution sealing grooves. The inner spherical surface of the outer rotor is provided with an inner sealing groove to form a sealing surface between the inner and outer rotors. The outer rotor has an outer sealing groove on its exterior, which forms a sealing surface with the stator base.

[0009] The stator base is provided with stator base oil holes around its perimeter. The stator cover and the stator base are fitted together to form a hollow cavity. The stator cover has a spherical auxiliary pair to assist the swing of the output shaft of the inner rotor.

[0010] The inner and outer rotors are nested together to form a composite assembly, which is installed in the stator base. The inner spherical surface of the outer rotor and the outer spherical surface of the inner rotor cooperate to form a sealing surface, and the outer spherical surface of the outer rotor and the inner spherical surface of the stator base cooperate to form a sealing surface. The rotor blade sealing groove is provided with a sealing ring so that the inner rotor blade and the outer rotor blade groove are nested to form two sealed cavities. The outer rotor sealing groove is provided with a sealing ring to form two sealed cavities. The oil distribution sealing groove (19, 20) is provided with a sealing ring so that the oil distribution groove and the stator base form two sealed fan-shaped grooves.

[0011] The present invention provides a two-degree-of-freedom hydraulic joint, wherein the sliding bearing has four surfaces, namely a spherical surface, a cylindrical surface, and two planes, which respectively cooperate with the inner rotor, the outer rotor, the stator base, and the stator cover.

[0012] The present invention provides a two-degree-of-freedom hydraulic joint, wherein the inner rotor blade has a rectangular cross-section to ensure that the inner rotor cannot spin within the inner cavity of the outer rotor, and the two parallel planes on the side of the outer rotor ensure that the outer rotor cannot spin within the stator base.

[0013] The present invention provides a dual-degree-of-freedom hydraulic joint, wherein the rotor blade sealing groove forms two independent sealed cavities with the inner rotor blade and the outer rotor blade groove; the outer rotor outer sealing groove forms two independent sealed cavities with the inner and outer rotor assembly and the stator base, and ensures that the two sealed cavities of the blade groove are independent of each other, thereby achieving that both pairs of sealed cavities are independent of each other.

[0014] The present invention provides a dual-degree-of-freedom hydraulic joint, wherein the oil distribution groove, the outer rotor oil hole, the stator base oil hole, and the oil distribution sealing groove constitute an oil distribution mechanism.

[0015] This invention presents a two-degree-of-freedom hydraulic joint that significantly reduces the overall mass of the robotic arm and simplifies the traditional, complex robotic arm transmission chain. Hydraulic drive can achieve greater driving force compared to electric drive, thus achieving both simplicity and efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the two-degree-of-freedom hydraulic joint structure of the present invention (stator omitted);

[0017] Figure 2 This is an exploded view of the inner rotor and outer rotor of the present invention;

[0018] Figure 3 This is a schematic diagram of the internal rotor structure of the present invention;

[0019] Figure 4This is a schematic diagram of the external rotor structure of the present invention;

[0020] Figure 5 This is a schematic diagram of the stator base structure of the present invention;

[0021] Figure 6 This is a schematic diagram of the stator cover structure of the present invention;

[0022] Figure 7 This is a schematic diagram of the sliding bearing structure of the present invention;

[0023] Figure 8 This is a schematic diagram of the inner ring oil cavity structure of the present invention;

[0024] Figure 9 This is a schematic diagram of the outer annular oil cavity structure of the present invention;

[0025] In the diagram: 1-Inner rotor; 2-Outer rotor; 3-Sliding bearing; 4-Stator base; 5-Stator top cover; 6, 7, 8, 9-Stator base oil holes; 10, 11-Outer rotor oil holes; 12-Outer rotor outer sealing groove; 13-Rotor blade sealing groove; 14-Outer rotor inner sealing groove; 15-Inner rotor blade; 16, 17-Oil distribution groove; 18-Output shaft; 19, 20-Oil distribution sealing groove. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings: This embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation methods are given, but the protection scope of the present invention is not limited to the following embodiments.

[0027] Example 1: As Figure 1-9 As shown, the dual-degree-of-freedom hydraulic joint involved in this embodiment includes an inner rotor, an outer rotor, a sliding bearing, an oil distribution mechanism, a sealing assembly, a stator cover, and a stator base. The nested structure of the inner and outer rotors is particularly crucial in achieving two independent degrees of freedom.

[0028] The inner rotor has a sphere in the middle, one end of which is the output shaft of the inner rotor, which is also the output shaft of the two-degree-of-freedom hydraulic joint, and the other end is the inner rotor swing blade with a rectangular cross section. The outer rotor and the inner rotor blade are nested together to form two cavities that control the first degree of freedom of movement. The oil in the two cavities controls the swing angle of the inner rotor blade, thereby controlling the angle of the extended shaft in the first degree of freedom, realizing one degree of freedom of rotation.

[0029] The outer rotor body is hemispherical, with its center coinciding with the center of the inner rotor. It has two parallel sides and internal blade grooves nested with the inner rotor blades. Internal sealing grooves create a sealing surface between the inner and outer rotors. The outer rotor has an external sealing groove that forms a sealing surface with the stator base. The nested inner and outer rotors are mounted in the stator base, forming two cavities with the hollow portion of the stator base. Oil in these cavities controls the outer rotor to drive the inner rotor in a direction perpendicular to the first degree of freedom, achieving the second degree of freedom. When the outer rotor drives the inner rotor to rotate along the second degree of freedom, it does not affect the first degree of freedom of the inner rotor, thus creating two independent movements, i.e., two independent degrees of freedom.

[0030] The outer rotor supplies oil to the inner rotor blades for oscillation through an oil distribution mechanism. The oil distribution method is that two oil holes on the stator base supply oil to the inner rotor blades for oscillation through the oil distribution groove on the side of the outer rotor and the oil holes on the oil distribution groove.

[0031] The stator cover and the stator base fit together to form a hollow space in the middle, which is used to nest the inner rotor and the outer rotor to form an assembly. The stator cover has a spherical pair to assist the swing of the inner rotor's extension shaft.

[0032] Sliding bearings play an auxiliary role. Each mating surface has a different design relative to the mating parts, with the aim of achieving the stability of rotation of each part, thereby improving the overall stability.

[0033] The inner and outer rotors are nested together, ensuring that the inner rotor blades oscillate along the direction of the outer rotor's inner cavity blade slots. This, in turn, allows the extended shaft to rotate along the direction of the outer rotor blade slots with the assistance of the spherical pair on the stator cover, achieving the first degree of freedom of rotation. The inner rotor blades have a rectangular cross-section to ensure that they do not rotate within the outer rotor cavity when oscillating within the outer rotor's inner cavity.

[0034] The inner and outer rotors form a composite assembly nested on the stator base. This nested assembly, mounted within the stator base, forms two cavities with the hollow portion of the base. Oil in these cavities controls the outer rotor to drive the inner rotor in a direction perpendicular to the first degree of freedom, achieving a second degree of freedom. The rotation of the inner rotor along this second degree of freedom by the outer rotor does not affect the inner rotor's first degree of freedom, thus creating two independent motions, or two independent degrees of freedom.

[0035] The two sides of the oil distribution mechanism of the outer rotor are parallel planes that fit tightly with the hollow part inside the stator base to achieve a sealing surface. The two parallel sides of the outer rotor ensure that the outer rotor does not spin when it moves in the direction of the second degree of freedom.

[0036] The inner and outer rotors are nested to achieve one degree of oscillation, and the inner and outer rotors are installed in the stator base to achieve another degree of oscillation. The rotation of the two degrees of freedom are independent of each other and do not affect each other.

[0037] The inner rotor blades have a rectangular cross-section to ensure that the inner rotor cannot spin within the inner cavity of the outer rotor. The two parallel planes on the side of the outer rotor also ensure that the outer rotor cannot spin within the stator base. These two constraints on the spin motion ensure that the output shaft of the two-degree-of-freedom hydraulic joint can only generate two independent degrees of freedom, and there is no third degree of freedom.

[0038] The sealing grooves of the inner rotor blades ensure that the inner rotor blades and the outer rotor blade grooves form two independent sealed cavities.

[0039] The sealing groove outside the outer rotor ensures that the two sealed cavities formed by the inner and outer rotor assembly and the stator base are independent of each other, and also ensures that the two sealed cavities of the blade slot are independent of each other, thus achieving that all four sealed cavities are independent of each other.

[0040] The stator base has two sets of four oil circuits: one set provides oil for the inner rotor and the other set provides oil for the outer rotor.

[0041] The oil distribution mechanism of the outer rotor consists of an oil distribution groove, outer rotor oil holes, stator oil holes, and seals. The oil distribution groove is a sector-shaped groove of a certain depth, surrounded by a seal. When the component containing the oil distribution groove (outer rotor) rotates (second degree of freedom, i.e., perpendicular to the outer rotor blade groove), the presence of the sector-shaped groove ensures that the two first degree of freedom motion control oil holes on the stator base are always connected to the two oil holes on the outer rotor, ensuring that the oil enters the two cavities of the inner rotor from the stator base, thereby driving the inner rotor blades to oscillate.

[0042] The sliding bearing has four surfaces: a spherical surface, a cylindrical surface, and two flat surfaces. These surfaces work in conjunction with other components to provide support and sealing for the rotation of the outer rotor, enabling the outer rotor of the hydraulic joint to rotate stably.

[0043] Example 2: Figure 1-9 As shown, the dual-degree-of-freedom hydraulic joint involved in this embodiment includes an inner rotor 1, an outer rotor 2, a sliding bearing 3, a stator base 4, and a stator cover 5.

[0044] Inner rotor 1 as Figure 3As shown, the center is a sphere, one end is the output shaft 18, and the other end is an inner rotor blade 15 with a rectangular cross-section. The inner rotor blade 15 is nested with the blade slot of the outer rotor 2. The inner rotor blade 15 has a rotor blade sealing groove 13 for placing a sealing ring to achieve a seal, ensuring that the inner rotor blade 15 and the outer rotor blade slot form two independent sealed cavities. The swing of the extended shaft is controlled by the swing of the inner rotor blade 15 within the blade slot of the outer rotor 2. The swing of the inner rotor blade 15 along the blade slot direction achieves rotation with degree of freedom a. The axes of the inner rotor output shaft 18 and the inner rotor blade 15 both pass through the center of the inner rotor 1 sphere; the rectangular cross-section of the inner rotor blade 15 ensures that the inner rotor achieves rotation with degree of freedom 1 without spin.

[0045] The stator base 4 and stator cover 5 are combined to form a spherical cavity in the middle. The inner rotor 1 and outer rotor 2 are nested in this cavity. The outer spherical surface of the outer rotor 2 mates with the inner spherical surface of the stator base to form a sealing surface. The outer spherical surface of the outer rotor 2 has a sealing groove 12, which is arc-shaped. A sealing element is installed in the groove to ensure that the sealed cavity formed by the outer rotor 2 and the stator base is independent of each other. The swing of the output shaft 18 is controlled by controlling the swing of the outer rotor 2. The center of the circle is the center of the inner rotor 1, which realizes the swing along the direction perpendicular to the blade groove of the outer rotor 2, that is, the rotation of the degree of freedom b perpendicular to the degree of freedom a. The outer rotor 2 has two parallel planes E and F on its side to ensure that the outer rotor does not spin during rotation.

[0046] The rotation of degree of freedom a is restricted by the blade slots of the outer rotor 2, allowing the blades of the inner rotor 1 nested within it to oscillate only along the direction of the blade slots. Furthermore, it is sealed by the outer rotor's outer sealing groove 12, ensuring that the two independent cavities A and B are unaffected by the sealed cavities C and D, thus achieving independent degrees of freedom. Similarly, the rotation of degree of freedom b is restricted by the inner spherical surface and inner plane of the stator base 4, allowing the outer rotor to rotate only along the direction of the inner spherical surface restricted by the inner plane of the stator base 4. This direction is perpendicular to the direction of the outer rotor's blade slots. Sealed by the sealing groove 12, it ensures that the two independent cavities C and D are unaffected by the sealed cavities A and B, achieving independent degrees of freedom. Thus, degrees of freedom a and b are mutually independent, realizing a two-degree-of-freedom rotation of the hydraulic joint. Since neither the inner nor outer rotor can spin, this two-degree-of-freedom hydraulic joint can prevent the output shaft from undergoing a third degree of freedom spin motion, stably achieving rotation of the two independent degrees of freedom.

[0047] The driving oil for the inner rotor rotation is achieved through a unique oil distribution mechanism. The oil enters the sealed oil distribution groove 16 through the stator base oil hole 6. 19 and 20 are oil distribution sealing grooves containing seals. Then, the oil enters the inner rotor 1 cavity A through the outer rotor oil hole 10 at the bottom of the oil distribution groove 16. Similarly, the oil in cavity B enters the oil distribution groove 17 through the oil hole 11 at the bottom of the oil distribution groove 17, and then flows out of the stator base 4 through the stator base oil hole 7.

[0048] To ensure smooth rotation between the inner rotor 1 and the outer rotor 2 without interference, a sliding bearing 3 is added. The side of the sliding bearing 3 that contacts the inner rotor 1 is spherical and concentric with it. The side that contacts the outer rotor 2 is cylindrical. The side that contacts the stator cover is flat. This flat surface ensures good contact between the sliding bearing 3 and the outer rotor 2, allowing it to rotate around the center of the inner rotor 1 along the surface of the stator base 4. The side that contacts the stator base 4 is similarly designed to further smooth the movement of the two degrees of freedom, while also providing a certain degree of sealing.

[0049] Example 3: Figure 1-9 As shown, the working process of a two-degree-of-freedom hydraulic joint involved in this embodiment is as follows:

[0050] The inner rotor 1 has a sphere in the center, and it rotates around the center of the sphere. One end of the sphere is the output shaft 18, and the other end is the inner rotor blade 15. The inner rotor blade 15 is nested within the blade slots of the outer rotor 2 to form an oil cavity. Figure 8 As shown. Oil flows into the outer rotor oil distribution mechanism through the stator base oil hole 6. The oil distribution mechanism consists of an oil distribution groove 16 and an outer rotor oil hole 10. The oil distribution groove ensures that the stator base oil hole 6 and the outer rotor oil hole 10 are connected when the outer rotor rotates on the spherical surface inside the stator base, achieving normal oil distribution. Oil enters the sealed cavity A through the outer rotor oil hole 10, applying pressure to the inner rotor blades 15, causing the inner rotor blades 15 to swing towards the sealed cavity B. Because the inner rotor 1 output shaft 18 and the inner rotor 1 blades are on the same straight line, the inner rotor 1 output shaft also swings accordingly. Then, the oil in the sealed cavity B flows into the oil distribution groove 17 through the outer rotor oil hole 11, and then flows out through the stator base oil hole 7. The reverse swing, i.e., the oil flows in the opposite direction, achieves control of the rotation along the blade slot direction of the outer rotor 2, i.e., degree of freedom a.

[0051] The inner and outer rotor assemblies are nested within the central cavity of the stator base 4 and the stator cover 5, and can rotate along the inner spherical surface of the stator base 4, with the center of rotation being the center of the inner rotor 1. The sealed cavity formed by the inner rotor 1, the outer rotor 2, and the stator base 4 is as follows: Figure 9As shown. Oil flows into the sealed cavity C through the stator base oil hole 8. Applying hydraulic pressure to the side of the outer rotor pushes it to rotate along the inner spherical surface of the stator base 4. Due to the nesting relationship between the inner rotor 1 and the outer rotor 2, the rotation of the outer rotor 2 is equivalent to the rotation of the inner rotor 1. The extension shaft of the inner rotor rotates along with the rotation of the inner rotor 1, with the center of rotation being the center of the inner rotor 1 sphere. As the volume of the sealed cavity C increases, the volume of the sealed cavity D decreases accordingly. Oil flows out through the stator base oil hole 9, and the reverse oscillation, i.e., the oil flows in the opposite direction, achieves control of the rotation along the inner spherical surface of the stator base 4, that is, rotation perpendicular to the direction of the blade slots of the outer rotor 2, which is the so-called degree of freedom b.

[0052] The rotation of the inner rotor relative to the outer rotor, and the rotation of the inner and outer rotor assembly relative to the stator base, achieve the rotation of the two different degrees of freedom of the dual-degree-of-freedom hydraulic joint, and the two degrees of freedom are independent of each other.

[0053] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A two-degree-of-freedom hydraulic joint, characterized by, The double-degree-of-freedom hydraulic joint comprises an inner rotor (1), an outer rotor (2), a sliding bearing (3), a stator base (4) and a stator upper cover (5); The inner rotor (1) is a sphere in the middle, one end is an inner rotor output shaft (18) which is also an output shaft of the double-degree-of-freedom hydraulic joint, and the other end is an inner rotor blade (15) with a rectangular cross section, both sides of the inner rotor blade (15) are provided with rotor blade sealing grooves (13); The outer rotor (2) is a semi-spherical body, the inner part of the outer rotor (2) is provided with a blade groove, the blade groove is nested with the inner rotor blade (15), the spherical center of the outer rotor (2) coincides with the spherical center of the inner rotor (1), the outer rotor (2) has two mutually parallel sides, the two mutually parallel sides are fan-shaped and have a hole at the center of the fan-shaped circle to place the sliding bearing (3), the fan-shaped side is provided with a pair of oil distribution grooves (16, 17), the pair of oil distribution grooves (16, 17) are respectively provided with corresponding outer rotor oil holes (10, 11), the bottoms of the pair of oil distribution grooves (16, 17) are respectively provided with corresponding oil distribution sealing grooves (19, 20), and the inner spherical surface of the outer rotor (2) is provided with an outer rotor inner sealing groove (14) to form a sealing surface between the inner and outer rotors; the outer part of the outer rotor (2) has an outer rotor outer sealing groove (12) which forms a sealing surface with the stator base (4); The stator base (4) is provided with stator base oil holes (6, 7, 8, 9) around, the stator upper cover (5) and the stator base (4) cooperate to form a hollow cavity in the middle, and the stator upper cover (5) has a spherical surface to assist the swinging of the output shaft (18) of the inner rotor (2); The combination of the inner rotor (1) and the outer rotor (2) nested with each other is installed in the stator base (4), the inner spherical surface of the outer rotor (2) cooperates with the outer spherical surface of the inner rotor (1) to form a sealing surface, the outer spherical surface of the outer rotor (2) cooperates with the inner spherical surface of the stator base (4) to form a sealing surface, the rotor blade sealing groove (13) is provided with a sealing ring to make the inner rotor blade (15) and the blade groove of the outer rotor (2) nested to form two closed cavities (A, B), and the outer rotor outer sealing groove (12) is provided with a sealing ring to form two sealed cavities (C, D); the pair of oil distribution sealing grooves (19, 20) are provided with sealing rings to make the corresponding oil distribution grooves (16, 17) and the stator base (4) form two corresponding closed fan-shaped grooves; The rotor blade sealing groove (13) makes the inner rotor blade (15) and the outer rotor blade groove form two mutually independent closed cavities (A, B); the outer rotor outer sealing groove (12) makes the inner and outer rotor combination and the stator base (4) form two mutually independent sealed cavities (C, D), and ensures that the two closed cavities (A, B) of the blade groove are independent of each other; The inner rotor blade (15) has a rectangular cross section, which ensures that the inner rotor (1) cannot rotate in the inner cavity of the outer rotor (2), and the two parallel planes of the side surface of the outer rotor (2) ensure that the outer rotor (2) cannot rotate in the stator base (4).

2. A dual degree of freedom hydraulic joint according to claim 1, characterized in that, The sliding bearing (3) has four surfaces, which are spherical surface, cylindrical surface, two planes, respectively matched with the inner rotor (1), the outer rotor (2), the stator base (4) and the stator upper cover (5).

3. A dual degree of freedom hydraulic joint according to claim 1, wherein, The oil distribution groove (16, 17), the outer rotor oil hole (10, 11), the stator base oil hole (6, 7) and the oil distribution sealing groove (19, 20) constitute an oil distribution mechanism.

Images