CN212318525U

CN212318525U - Rigid-flexible two-stage locking ball joint

Info

Publication number: CN212318525U
Application number: CN201820219776.6U
Authority: CN
Inventors: 李鹏; 宋国立
Original assignee: Shenzhen Graduate School Harbin Institute of Technology
Current assignee: Shenzhen Graduate School Harbin Institute of Technology
Priority date: 2018-02-08
Filing date: 2018-02-08
Publication date: 2021-01-08
Anticipated expiration: 2028-02-08

Abstract

The utility model discloses a rigid-flexible two-stage locking ball joint, wherein a two-stage piston is arranged in the ball joint, and the ball joint has a two-stage locking state; when the fluid pressure is not enough to push the two-stage pistons at the same time, the ball joint is in a flexible locking state, and when the fluid pressure can push the two-stage pistons at the same time, the ball joint is in a rigid locking state. The spherical joint and the head and the tail ends of the sleeve are fixed through the connecting sleeve to form a spherical joint connecting rod, and then two or more spherical joint connecting rods are connected to form a multi-degree-of-freedom operating arm which can position tools or surgical instruments; when different pressures are applied to the connecting rods, the locking state of the ball joint can be controlled to adapt to different joint loads.

Description

Rigid-flexible two-stage locking ball joint

Technical Field

The utility model belongs to the field of medical equipment, concretely relates to joint locking device.

Background

In medical surgery and medical experiment, since a plurality of instruments are used in the surgery and experiment, an operator cannot operate many instruments at the same time, and an additional assistant is required to perform the surgery and experiment. Increases the manpower expenditure, and if the operation and experiment time is too long, the operator and the assistant are easy to fatigue, and the handheld instrument is unstable. There is therefore a need for a device that will assist the operator in the stable positioning of surgical instruments and laboratory tools for different tasks.

Patent CN201710683947.0 discloses a medical auxiliary instrument solution, in which a screw pair squeezing ball joint configuration mode is adopted for locking. Firstly, this approach does not allow to lock and unlock all kinematic joints simultaneously; secondly, the locking principle is that the rigid part extrudes the rigid part to generate friction force to limit the relative movement between the parts, and the flexibility of multi-stage rigid and flexible locking is not provided.

SUMMERY OF THE UTILITY MODEL

The utility model provides a hard and soft two-stage locking ball joint is in order to solve in medical treatment and the medical science experiment need centre gripping operation instrument and apparatus operator can not the concurrent operation, and a lot of apparatus need the problem of extra assistant assistance, utilizes this locking joint can constitute the operating arm of many joint configurations, can fix a position surgical instruments and apparatus. The problem of operating personnel can not operate a plurality of operation instruments and apparatus simultaneously is solved. The locking joint has two-stage locking states, a flexible locking state and a rigid locking state, and is suitable for locking requirements under different loading conditions. When the fluid pressure is not enough to push the two-stage pistons at the same time, the ball joint is in a flexible locking state, and when the fluid pressure can push the two-stage pistons at the same time, the ball joint is in a rigid locking state. The utility model discloses a connecting sleeve links to each other two or more ball joint connecting rods with the fixed ball joint that forms in ball joint and sleeve both ends, can form multi freedom operation arm again, can fix a position surgical instruments or laboratory glassware, can allow a plurality of laboratory glassware of experimenter concurrent operation, improves experiment efficiency and success rate. The spherical joint and the head and the tail ends of the sleeve are fixed through the connecting sleeve to form a spherical joint connecting rod, and then two or more spherical joint connecting rods are connected to form a multi-degree-of-freedom operating arm which can position tools or surgical instruments; when different pressures are applied to the connecting rods, the locking state of the ball joint can be controlled to adapt to different joint loads.

A rigid-flexible two-stage locking ball joint is characterized by comprising a ball joint module, wherein the ball joint module consists of a joint sleeve, a ball joint cover, a spherical part, a ball joint metal bushing, a connecting rod, a main piston, a secondary piston, a spring, a sealing ring A, a fluid quick joint and a sealing ring B; one end of the spherical joint cover is provided with an external thread which is matched with an internal thread arranged on a joint sleeve, and an inner cavity structure matched with the plane structure of the main piston is arranged at the position, close to the external thread, of the joint sleeve; the spherical joint cover is connected with the joint sleeve through threads, the spherical joint cover and the joint sleeve are matched to seal a spherical part, a main piston and a secondary piston in an inner cavity, the spherical part is installed in the spherical joint cover, a spherical joint metal bushing is embedded in the spherical part, and the spherical joint metal bushing is fixedly connected with a connecting rod; the spherical part is contacted with the main piston, the main piston is contacted with one end of the spring, the other end of the spring is contacted with the secondary piston, the spring presses the main piston on the spherical part and presses the secondary piston at the bottom of the joint sleeve, and the main piston and the secondary piston are sleeved with a sealing ring A; the sealing ring B is arranged on the end surface of the main piston, and the fluid quick connector is arranged at the tail part of the joint sleeve; the ball joint module is connected with the connecting rod to form a joint connecting rod;

the main piston is composed of a plane structure, a spherical bulge, a sealing ring groove, an end face sealing ring groove, a shaft face and an inner hole, wherein the spherical bulge and the joint ball are continuously tangent; the outer circumference of one end of the main piston is provided with a plane structure, the plane structure is matched with the shape of an inner cavity of the joint sleeve, the plane structure is used for ensuring that the main piston does not rotate when sliding back and forth in the joint sleeve, one end of the main piston is provided with an inwards concave cambered surface, the cambered surface is provided with spherical bulges, the spherical bulges are arranged towards the axis of the main piston according to a rule from large to small, and when the diameter of the spherical bulges is reduced, the number of the bulges uniformly distributed in the circumferential direction is increased; the diameter of the spherical bulge is reduced when the spherical bulge is close to the axis, but the section of the spherical bulge is always tangent to the excircle of the spherical part when the spherical part is contacted with the main piston, so that the characteristic that the spherical bulge is continuously tangent to the joint ball is formed; a seal ring groove is formed in the main piston and used for placing a seal ring A in the seal ring groove to form a seal structure; an end face sealing ring groove is formed in the end face of the other end of the main piston, and a sealing ring B is placed in the end face sealing ring groove to isolate the secondary piston from the main piston; the shaft surface of the main piston is sleeved with a spring, the main piston is provided with an inner hole, the minimum distance between the bottom surface of the inner hole and the cambered surface arranged at one end of the main piston is greater than 0.01mm, and the inner hole is used for destroying the bottom unloading pressure of the inner hole when the pressure applied to the main piston is too large.

Preferably, the head end and the tail end of the curved connecting rod are respectively connected with a ball joint module, a three-way joint is arranged in the middle of the curved connecting rod, a fluid quick connector of the ball joint module is connected with the three-way joint through a hose, an end cover of the three-way joint is fixed on the curved connecting rod to form a joint connecting rod, and fluid is introduced into the three-way joint to control the locking states of the two ball joint modules simultaneously. When one ball joint module is fixed on the base and the other ball joint module is connected with an experimental tool or a surgical instrument, the connecting rod can play a role in positioning. The user can operate the connecting rod without fatigue and can simultaneously operate a plurality of experimental tools and surgical instruments.

Preferably, the main piston is matched with the spherical part, and when no fluid is filled in, the cavity formed by the main piston and the spherical joint cover under the elastic force of the spring allows the spherical part to rotate; the same applies to the cavity formed by the concentric venting main piston, the through-center spherical part and the spherical joint cover.

Preferably, the spherical bulge on the main piston is pressed into the surface of the spherical part when compressed fluid is filled into the cavity, and the surface of the spherical part is restored when the fluid pressure is removed; the same applies to the spherical projection of the concentrically vented main piston and to the through-center spherical part.

Preferably, the ball joint module can be a concentric ventilation ball joint, and the concentric ventilation ball joint consists of a joint sleeve, a ball joint cover, a concentric spherical part, a ball joint metal bushing, a hose, a concentric ventilation main piston, a secondary piston, a sliding joint, a sealing ring, an inner ring sealing ring and a fluid quick joint; the spherical joint cover is connected with the joint sleeve through threads, the inner cavity of the spherical joint cover is provided with an inwards concave spherical surface, and no gap exists after the hollow spherical part is placed in the spherical joint cover; a ball joint metal bushing is embedded on the through spherical part to allow the hose to pass through the middle; the concentric ventilation main piston and the secondary piston are sleeved with a sealing ring A which can slide in the inner cavity of the joint sleeve; a spring is arranged between the concentric ventilation main piston and the secondary piston, and an inner ring sealing ring is arranged on an inner ring of the secondary piston to allow the secondary piston to slide back and forth on the long shaft surface; the sliding joint is provided with a sealing ring and can slide in the inner cavity of the concentric ventilation main piston; one end of the sliding joint is provided with a hose, and the fluid quick joint is arranged at the tail part of the joint sleeve; the concentric ventilation main piston is composed of a plane structure, a spherical bulge, a sealing ring groove, an end face sealing ring groove, a long axial face, a step and a sliding joint cavity, wherein the spherical bulge and a joint ball are continuously tangent.

Preferably, the ball joint module and the concentric vent ball joint can be combined into a ball joint connecting rod by a curved connecting rod and a joint sleeve; the articulated links may be formed by expanding the number of curved connecting rods and articulated sleeves.

Preferably, the slip joint, sealing ring and hose are slidable within the inner chamber of the concentric vent main piston.

Preferably, the main piston and the concentric ventilation main piston are made of metal, ceramic and hard plastic materials, and the spherical parts and the hollow spherical parts are made of nonmetal and rubber materials; the hardness of the materials of the main piston and the concentric ventilation main piston is greater than that of the materials of the spherical part and the through spherical part.

Preferably, a spring is arranged between the main piston and the secondary piston; a spring is arranged between the concentric ventilation main piston and the secondary piston; the spring is a part made of elastic structure and materials which can generate resistance force when compressed and can restore to the original state when pressure is relieved.

The beneficial effects of the utility model reside in that: the utility model discloses based on two-stage piston structure, utilize different fluid pressure to promote the piston motion and then restrict the ball joint motion, reach the purpose of rigid locking or flexible locking. The rigid-flexible two-stage locking ball joint is designed into a single module through modular design, and a mechanical arm configuration is formed through the expansion connection among the modules, so that tasks which can be completed by some mechanical arms can be completed, for example, an operation arm formed by the ball joint is used for positioning an operation tool and an operation instrument in a three-dimensional space, the excessive fatigue of a doctor can be avoided, the labor intensity of the doctor is reduced, and the fatigue is avoided after long-time operation; the experimental tool is positioned by utilizing the operation arm, so that an experimenter can operate a plurality of experimental tools simultaneously, and the experimental efficiency and the success rate are improved.

Drawings

Fig. 1 is an external structure view of a rigid-flexible two-stage locking ball joint of the present invention.

Fig. 2 is a sectional structure view of the two-stage locking ball joint of the present invention.

Fig. 3 is a diagram of a main piston structure a of a rigid-flexible two-stage locking ball joint of the present invention.

Fig. 4 is a diagram of a main piston structure b of a rigid-flexible two-stage locking ball joint of the present invention.

Fig. 5 is a locking principle a diagram of the two-stage locking ball joint of the present invention.

Fig. 6 is a locking principle b diagram of the two-stage locking ball joint of the present invention.

Fig. 7 shows the joint module expansion mode of the two-stage rigid-flexible locking ball joint of the present invention.

Fig. 8 is a concentric ventilation type structure diagram of the rigid-flexible two-stage locking ball joint of the present invention.

Fig. 9 is a structural view of a concentric ventilation type master piston of a rigid-flexible two-stage locking ball joint of the present invention.

Fig. 10 is a diagram of a concentric ventilation type master piston structure b of a rigid-flexible two-stage locking ball joint of the present invention.

Fig. 11 is an extension of the concentric ventilation type of the rigid-flexible two-stage locking ball joint of the present invention.

Fig. 12 is an operation arm extended from the concentric ventilation type of the rigid-flexible two-stage locking ball joint of the present invention.

In the figure: 1/ball joint module; 1-1/joint sleeve; 1-2/ball joint cover; 1-3/spherical part; 1-4/ball joint metal bushing; 1-5/connecting rod; 1-6/primary piston; 1-7/two-stage piston; 1-8/spring; 1-9/sealing ring A; 1-10/fluid quick connector; 1-11/sealing ring B; 2-1/plane structure; 2-2/spherical bulge; 2-3/the characteristic that the spherical bulge is continuously tangent to the joint ball; 2-4/sealing ring groove; 2-5/end face seal ring groove; 2-6/axial plane; 2-7/inner hole; 3-1/curved connecting rod; 3-2/tee joint end cap; 3-3/tee joint; 4/concentric vent ball joint; 4-3/through-center spherical part; 4-4/ball joint metal bushing; 4-5/hose; 4-6/concentric vent main piston; 4-7/two-stage piston; 4-8/sliding joint; 4-9/sealing ring; 4-10/inner ring sealing ring; 5-1/major axis plane; 5-2/step; 5-3/sliding joint cavity; 6-1/connecting sleeve; 6-2/hose; 6-3/exhaust valve.

6-4 is marked and not said

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments.

The first embodiment is as follows:

referring to fig. 1, the rigid-flexible two-stage locking ball joint of the present invention has an external basic structure comprising a joint sleeve 1-1, a ball joint cover 1-2, a ball part 1-3 and a fluid quick coupling 1-10. Wherein the ball joint cover 1-2 is connected with the joint sleeve 1-1 through threads, and the outer circumference of the ball joint cover 1-2 is provided with a screwing structure which can screw the ball joint cover and the joint sleeve; the fluid quick connector 1-10 is arranged at the tail part of the joint sleeve 1-1 and is a fluid inlet;

referring to fig. 2, the ball joint module is composed of a ball joint metal bushing a1-4 embedded in a spherical part 1-3, and a connecting rod 1-5 constituting a ball joint movement part. The main piston 1-6 and the secondary piston A1-7 are sleeved with sealing rings 1-9 which can slide in the inner cavity of the joint sleeve 1-1; a spring 1-8 is arranged between the main piston 1-6 and the secondary piston A1-7, the spring 1-8 presses the main piston 1-6 on the spherical part 1-3, the secondary piston A1-7 is pressed at the bottom of the joint sleeve 1-1, and the secondary piston A1-7 and the joint sleeve 1-1 form a closed cavity;

referring to fig. 3-4, the structure of the main piston 1-6 is composed of a plane structure 2-1, a spherical bulge 2-2, a continuous tangent feature 2-3 of the spherical bulge and a joint ball, a seal ring groove 2-4, an end face seal ring groove 2-5, an axial surface 2-6 and an inner hole 2-7; the outer circumference of one end of the main piston 1-6 is provided with a plane structure 2-1, the plane structure 2-1 is matched with the shape of the inner cavity of the joint sleeve 1-1, and the plane structure 2-1 is used for ensuring that the main piston 1-6 does not rotate when sliding back and forth in the joint sleeve 1-1; the spherical bulge 2-2 approaches to the axis of the main piston 1-6 in a regular way from large to small, and when the diameter of the spherical bulge 2-2 is gradually reduced, the number of the bulges uniformly distributed in the circumferential direction is more dense, as shown in figure 3 (a); the diameter of the spherical bulge 2-2 is reduced when the spherical bulge is close to the axis, but the section of the spherical bulge is always tangent to the excircle of the spherical part 1-3, so that the characteristic 2-3 that the spherical bulge is continuously tangent to the joint ball is formed; the sealing ring grooves 2-4 are used for placing sealing rings A1-9 therein to form sealing structures; a sealing ring B1-11 is arranged in the end face sealing ring groove 2-5 to isolate the secondary piston A1-7 from the main piston 1-6; the springs 1-8 are sleeved on the shaft surface 2-6, the thickness between the bottom of the inner hole 2-7 and the arc surface of the main piston 1-6 is at least 0.01mm, when the pressure is too large, the inner hole 2-7 is damaged, and the pressure is unloaded.

Referring to fig. 5(a), when compressed fluid enters the cylindrical cavity of the joint sleeve 1-1 through the fluid quick coupling 1-10, the secondary piston A1-7 is pushed to approach the main piston 1-6, when the pressure is not enough to compress the spring 1-8, so that the secondary piston A1-7 and the main piston 1-6 are integrated, the ball joint is in a flexible locking state, and the locking effect is that the spring 1-8 presses the main piston 1-6 on the spherical part 1-3;

further, referring to FIG. 6(b), when the pressure is great enough as the pressurized fluid enters the cavity of the joint sleeve 1-1 through the fluid quick connector 1-10, the fluid will push the secondary piston A1-7 toward the primary piston 1-6 and compress the spring 1-8 until the secondary piston A1-7 is in contact with the primary piston 1-6 and the primary piston 1-6

Figure 245403DEST_PATH_GDA0002733655960000071

Sealing ring B1-11; the ball joint reaches a rigid locking state, and the fluid pushes the secondary piston A1-7 and the main piston 1-6 to be compressedBall parts 1-3.

Referring to fig. 7, the ball joint module 1 may constitute a joint link by being connected with curved connecting rods 3-1 of various shapes. The head end and the tail end of the curved connecting rod 3-1 are respectively connected with a ball joint module 1, the middle part of the curved connecting rod 3-1 is provided with a three-way joint 3-3, a quick joint 1-10 of the ball joint module 1 is connected with the three-way joint 3-3 through a hose, then an end cover 3-2 of the three-way joint is fixed on the curved connecting rod 3-1 to form a joint connecting rod, and fluid is introduced into the three-way joint 3-3 to simultaneously control the locking state of the two ball joint modules 1. When one ball joint module 1 is fixed on the base and the other ball joint module 1 is connected with an experimental tool or a surgical instrument, the connecting rod can play a role in positioning. The operating arm formed by a plurality of connecting rods can be used for simultaneously operating a plurality of experimental tools and surgical instruments, so that the labor intensity of doctors is reduced.

Example two:

the embodiment is changed on the basis of the first embodiment, in the embodiment, the ball joint module 1 in the first embodiment is changed into the concentric venting ball joint 4 with a concentric venting structure, and the concentric venting structure can maintain the locking function and simultaneously allow the fluid of the concentric venting ball joint 4 to flow into the inner cavity of the adjacent concentric venting ball joint 4 through the internal flow passage of the local joint. When the concentric vent structure concentric vent ball joint 4 is expanded, a fluid inlet can be used to see that the inner cavities of other concentric vent ball joints 4 are completely filled.

Referring to fig. 8, the concentric venting ball joint 4 consists of a joint sleeve 1-1, a ball joint cover 1-2, a hollow spherical part 4-3, a ball joint metal bushing B4-4, a hose 4-5, a concentric venting main piston 4-6, a secondary piston B4-7, a sliding joint 4-8, a sealing ring 4-9, an inner ring sealing ring 4-10 and a fluid quick joint 1-10. Wherein the ball joint cover 1-2 is connected with the joint sleeve 1-1 through screw threads, the inner cavity of the ball joint cover 1-2 is provided with an inwards concave spherical surface, and a through spherical part 4-3 is not provided with a gap after being placed; a ball joint metal bushing B4-4 is embedded on the through spherical part 4-3 and is of a hollow sleeve structure, and the hose 4-5 is allowed to pass through the middle; the concentric ventilation main piston 4-6 and the secondary piston B4-7 are sleeved with sealing rings 1-9 which can slide in the inner cavity of the joint sleeve 1-1; a spring 1-8 is arranged between the concentric ventilation main piston 4-6 and the secondary piston B4-7, the spring 1-8 presses the concentric ventilation main piston 4-6 on the through spherical part 4-3, and simultaneously presses the secondary piston B4-7 on the bottom of the joint sleeve 1-1; an inner ring sealing ring 4-10 is further inlaid on the inner ring of the secondary piston B4-7, so that the secondary piston B4-7 can slide back and forth on the long shaft surface 5-1. A sealing ring 4-9 is arranged on the sliding joint 4-8 and can slide in an inner cavity 5-4 of the concentric ventilation main piston 4-6, and one end of the sliding joint 4-8 is provided with a hose 4-5; the fluid quick connector 1-10 is arranged at the tail part of the joint sleeve 1-1 and is a fluid inlet.

Referring to fig. 9-10, the structure of the concentric ventilation main piston 4-6 is composed of a plane structure 2-1, a spherical bulge 2-2, a continuous tangent feature 2-3 of the spherical bulge and a joint ball, a seal ring groove 2-4, an end face seal ring groove 2-5, a long shaft face 5-1, a step 5-2 and a sliding joint cavity 5-3; the plane structure 2-1 is matched with the inner cavity of the joint sleeve 1-1 and allows the concentric ventilation main piston 4-6 to slide back and forth in the joint sleeve 1-1 without rotating; the spherical bulge 2-2 approaches to the axis of the concentric ventilation main piston 4-6 in a regular way from large to small, and when the diameter of the spherical bulge 2-2 is gradually reduced, the number of the bulges uniformly distributed in the circumferential direction is more dense, as shown in figure 9 (a); the diameter of the spherical bulge 2-2 is reduced when the spherical bulge is close to the axis, but the section of the spherical bulge is always tangent to the excircle of the through spherical part 4-3 to form a characteristic 2-3 that the spherical bulge and the joint ball are continuously tangent; a sealing ring A1-9 can be placed in the sealing ring groove 2-4 to form a sealing structure; a sealing ring B1-11 is arranged in the end face sealing ring groove 2-5 to isolate a secondary piston B4-7 from a concentric ventilation main piston 4-6; the long shaft surface 5-1 can be provided with a spring 1-8, the sliding joint cavity 5-3 allows the sliding joint 4-8 to slide back and forth, and the step 5-2 has a limiting effect on the sliding joint 4-8.

Referring to fig. 11, when the concentric air passing ball joint 4 is connected with the connecting sleeve 6-1 end to end, the hose 6-2 is connected with the fluid quick connectors 1-10 of the two ball joints, and the exhaust valve 6-3 is arranged on the hose 4-5 at the head of one of the ball joints to form a connecting rod of the concentric air passing ball joint 4. When compressed fluid is introduced into one of the ball joints, the fluid fills the inner cavities of all the ball joints to lock all the ball joints.

Referring to fig. 12, the joint linkage of fig. 11 is expanded to a configuration of four ball joints and two connecting sleeves 6-1, and compressed fluid is introduced at the endmost flexible tube 4-5, and the fluid will fill all four ball joint lumens through internal flexible tube connections and flow channels to achieve locking of the four ball joints. When the exhaust valve 6-3 is pressed down, the fluid is discharged, and the ball joint can realize free movement under the control of a human hand.

Example three:

the air vent valve 6-3 in the second embodiment can also seal the hose 4-5 at one end of the concentric balloon joint 4 at the tail end, and other parts are not changed, so that the locking function is realized.

Example four:

the embodiment is obtained by slightly changing on the basis of the first embodiment, the size of the spherical bulge 2-2 of the main piston 1-6 is kept unchanged and is tangent with the spherical part 1-3, other parts are kept unchanged, and the rigid-flexible two-stage locking function can be realized.

The above, only be the concrete implementation of the preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art is in the technical scope of the present invention, according to the technical solution of the present invention and the utility model, the concept of which is equivalent to replace or change, should be covered within the protection scope of the present invention.

Claims

1. A rigid-flexible two-stage locking ball joint is characterized by comprising a ball joint module (1), wherein the ball joint module (1) consists of a joint sleeve (1-1), a ball joint cover (1-2), a spherical part (1-3), a ball joint metal bushing A (1-4), a connecting rod (1-5), a main piston (1-6), a secondary piston A (1-7), a spring (1-8), a sealing ring A (1-9), a fluid quick joint (1-10) and a sealing ring B (1-11); an external thread is arranged at one end of the spherical joint cover (1-2), the external thread is matched with an internal thread arranged on the joint sleeve (1-1), and an inner cavity structure matched with the plane structure (2-1) is arranged at the position, close to the external thread, of the joint sleeve (1-1); the spherical joint cover (1-2) is connected with the joint sleeve (1-1) through threads, the spherical joint cover (1-2) is matched with the joint sleeve (1-1) to seal a spherical part (1-3), a main piston (1-6) and a secondary piston A (1-7) in an inner cavity, the spherical part (1-3) is installed in the spherical joint cover (1-2), a spherical joint metal bushing A (1-4) is embedded in the spherical part (1-3), and the spherical joint metal bushing A (1-4) is fixedly connected with a connecting rod (1-5); the spherical part (1-3) is in contact with the main piston (1-6), the main piston (1-6) is in contact with one end of the spring (1-8), the other end of the spring (1-8) is in contact with the secondary piston A (1-7), the main piston (1-6) is pressed on the spherical part (1-3) by the spring (1-8), the secondary piston A (1-7) is pressed at the bottom of the joint sleeve (1-1), and the main piston (1-6) and the secondary piston A (1-7) are sleeved with a sealing ring A (1-9); the sealing ring B (1-11) is arranged on the end surface of the main piston (1-6), and the fluid quick connector (1-10) is arranged at the tail part of the joint sleeve (1-1); the ball joint module (1) is connected with the connecting rod to form a joint connecting rod;

the main piston (1-6) is composed of a plane structure (2-1), a spherical bulge (2-2), a characteristic (2-3) that the spherical bulge is continuously tangent with a joint ball, a seal ring groove (2-4), an end face seal ring groove (2-5), a shaft face (2-6) and an inner hole (2-7); the outer circumference of one end of the main piston (1-6) is provided with a plane structure (2-1) which is matched with the shape of an inner cavity of the joint sleeve (1-1), the plane structure (2-1) is used for ensuring that the main piston (1-6) does not rotate when sliding back and forth in the joint sleeve (1-1), one end of the main piston (1-6) is provided with an inwards concave arc surface, the arc surface is provided with spherical bulges (2-2), the spherical bulges (2-2) are arranged towards the axis of the main piston (1-6) in a rule from large to small, and when the diameter of the spherical bulges (2-2) is reduced, the number of the bulges uniformly distributed in the circumferential direction is increased; the diameter of the spherical bulge (2-2) is reduced when the spherical bulge is close to the axis, but the section of the spherical bulge is always tangent to the excircle of the spherical part (1-3) when the spherical part is contacted with the main piston (1-6), so that the characteristic (2-3) that the spherical bulge is continuously tangent to the joint ball is formed; a seal ring groove (2-4) is formed in the main piston (1-6), and the seal ring groove (2-4) is used for placing a seal ring A (1-9) therein to form a seal structure; an end face seal ring groove (2-5) is formed in the end face of the other end of the main piston (1-6), and a seal ring B (1-11) is placed in the end face seal ring groove (2-5) to isolate the secondary piston A (1-7) from the main piston (1-6); the axial surface (2-6) of the main piston (1-6) is sleeved with a spring (1-8), the main piston (1-6) is provided with an inner hole (2-7), the minimum distance between the bottom surface of the inner hole (2-7) and the cambered surface arranged at one end of the main piston (1-6) is greater than 0.01mm, and the inner hole (2-7) is used for destroying the bottom unloading pressure of the inner hole (2-7) when the pressure applied to the main piston (1-6) is too large.

2. A rigid-flexible two-stage locking ball joint as claimed in claim 1, wherein the main piston (1-6) is matched with the ball part (1-3), and when no fluid is filled, the cavity formed by the main piston (1-6) and the ball joint cover (1-2) under the elastic force of the spring (1-8) allows the ball part (1-3) to rotate; the same applies to the cavity formed by the concentric vent main piston (4-6), the through spherical part (4-3) and the spherical joint cover (1-2).

3. A rigid-flexible two-stage locking ball joint as claimed in claim 1, wherein the spherical protrusions (2-2) on the main piston (1-6) are pressed into the surface of the spherical parts (1-3) when the compressed fluid is filled into the cavity, and the surface of the spherical parts (1-3) is restored when the fluid pressure is removed.

4. A rigid-flexible two-stage locking ball joint according to claim 1, characterized in that the ball joint module (1) is combined with the curved connecting rod (3-1) and the joint sleeve (1-1) to form a ball joint link.

5. A rigid-flexible two-stage locking ball joint as claimed in claim 1, wherein the ball joint module (1) can be a concentric venting ball joint (4), and the concentric venting ball joint (4) is composed of a joint sleeve (1-1), a ball joint cover (1-2), a concentric spherical part (4-3), a ball joint metal bushing B (4-4), a hose (4-5), a concentric venting main piston (4-6), a secondary piston B (4-7), a sliding joint (4-8), a sealing ring (4-9), an inner ring sealing ring (4-10) and a fluid quick joint (1-10); the spherical joint cover (1-2) is connected with the joint sleeve (1-1) through threads, and the inner cavity of the spherical joint cover (1-2) is provided with an inwards concave spherical surface and is matched with the through spherical part (4-3); a ball joint metal bushing B (4-4) is embedded on the through spherical part (4-3) to allow the hose (4-5) to pass through the middle; the concentric ventilation main piston (4-6) and the secondary piston B (4-7) are sleeved with sealing rings A (1-9) which can slide in the inner cavity of the joint sleeve (1-1); a spring (1-8) is arranged between the concentric ventilation main piston (4-6) and the secondary piston B (4-7), an inner ring of the secondary piston B (4-7) is provided with an inner ring sealing ring (4-10) to allow the secondary piston B (4-7) to slide back and forth on the long shaft surface (5-1); the sliding joint (4-8) is provided with a sealing ring (4-9) which can slide in the inner cavity of the concentric ventilation main piston (4-6); one end of the sliding joint (4-8) is provided with a hose (4-5), and the fluid quick joint (1-10) is arranged at the tail part of the joint sleeve (1-1); the concentric ventilation main piston (4-6) is composed of a plane structure (2-1), a spherical protrusion (2-2), a characteristic (2-3) that the spherical protrusion is continuously tangent with a joint ball, a seal ring groove (2-4), an end face seal ring groove (2-5), a long shaft face (5-1), a step (5-2) and a sliding joint cavity (5-3).

6. A rigid-flexible two-stage locking ball joint according to claim 5, characterized in that the sliding joint (4-8), the sealing ring (4-9) and the hose (4-5) slide in the inner cavity of the concentric venting main piston (4-6).

7. A rigid-flexible two-stage locking ball joint as claimed in claim 1, wherein springs (1-8) are mounted between the primary piston (1-6) and the secondary piston a (1-7); the springs (1-8) are parts made of elastic structures and materials which can generate resistance force when compressed and can restore the original shape when pressure is relieved.