Method for infinitely adjusting axial rigidity

Abstract

The invention discloses a method for infinitely adjusting axial rigidity, which is characterized in that an elastic component is connected between two axial butt-joint components, so that force transmission is realized by extruding the elastic component no matter the two axial butt-joint components are mutually extruded and mutually pulled outwards in the axial direction; then the axial rigidity is adjusted by changing the pretightening force of the elastic component in the axial direction; the adjusting device is characterized in that a bolt axially arranged at one end of the elastic component extrudes the elastic component to change the pre-tightening force of the elastic component, and adjustment is achieved. The connecting arm has the advantages that stepless adjustment of the axial rigidity of the connecting arm can be better achieved, and the adjusting process is simpler, more stable and more reliable.

Description

Technical Field

[0001] The invention relates to a technology for adjusting the stiffness of a connecting arm of an orthopedic external fixation bracket, and in particular to a method for steplessly adjusting the axial stiffness. Background Art

[0002] During the rehabilitation process of fracture patients, especially limb fracture patients, an orthopedic external fixator is usually required to fix the fracture site to avoid secondary injury to the fracture site during the rehabilitation process and accelerate the growth and rehabilitation of the fracture site. Existing orthopedic external fixators are usually composed of two fixing rings and a connecting arm connected between the fixing rings. When in use, bone pins are installed on the fixing rings and fixed at both ends of the limb fracture site, and then the relative positions of the fixing rings are adjusted by the connecting arm with a telescopic function to keep the limb in a normal growth state.

[0003] In conventional orthopedic external fixators, although the connecting arm can be adjusted to change its length, its own stiffness is often not adjustable. The bone growth at different stages of the limb fracture healing process is different, resulting in different requirements for the stiffness and flexibility of the fixed support, making conventional orthopedic external fixators unable to meet the needs. In order to improve the above defects, it is necessary to consider installing a variable stiffness adjustment joint on the connecting arm of the orthopedic external fixator to adjust the axial stiffness of the connecting arm as needed, so that it can meet the changing requirements of the support stiffness at different stages of the bone healing process.

[0004] The applicant has applied for a patent. CN202411638341.1 has disclosed a method for adjusting the axial stiffness of a connecting arm, which is characterized in that an elastic member is connected and arranged between two axially docking members, so that whether the two axially docking members are mutually squeezed or pulled outward in the axial direction, the force transmission is achieved by squeezing the elastic member, and then the axial stiffness of the connecting arm is adjusted by changing the preload force of the elastic rubber ring in the axial direction. The invention can better realize the stepless adjustment of the axial stiffness of the connecting arm, while improving the convenience of adjustment, and can realize the direct switching control of the connecting arm from flexibility to full stiffness; it has the advantages of convenient adjustment, large adjustable range, better stability, etc. However, the scheme still has the following defects: 1 In the scheme, a rotatable nut is used to squeeze the elastic member to achieve the stepless adjustment of its preload force. In order to accommodate the right-end locking nut and the stiffness adjustment nut, a larger window has to be processed on the shell, which greatly weakens the strength and stiffness of the shell, has higher processing costs, and has worse structural stability. 2 The window opening size reserved on the shell for adjusting the stiffness adjustment nut is limited, and it is laborious and inconvenient to turn it when it is necessary to adjust to a larger stiffness. 3 In order to limit the relative rotation between the shaft-shaped docking member and the shell, a rectangular groove is machined inside the shell to match the positioning pin installed on the shaft-shaped docking member; keyways are machined on the stiffness adjustment ring and the shaft-shaped docking member to accommodate the sliding key, and then the sliding key is used to limit the relative rotation between the stiffness adjustment ring and the shaft-shaped docking member, which is more complicated and costly to process.

[0005] Therefore, how to further improve it to make its structure simpler, more stable and reliable, and facilitate the implementation of the adjustment process has become a problem that needs to be further considered and solved by technical personnel in this field. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a method for steplessly adjusting the axial stiffness of the connecting arm, which can better achieve stepless adjustment of the axial stiffness and make the adjustment process simpler, more stable and reliable.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for steplessly adjusting axial stiffness comprises: an elastic member is connected and arranged between two axially butted members, so that whether the two axially butted members are mutually squeezed or pulled outward in the axial direction, force transmission is achieved by squeezing the elastic member, and then the axial stiffness is adjusted by changing the axial preload of the elastic member; the method is characterized in that the preload of the elastic member is changed by squeezing the elastic member through a bolt arranged in the axial direction at one end of the elastic member, so as to achieve adjustment.

[0008] In this way, this method directly relies on changing the degree of axial compression of the elastic rubber ring to change its axial preload to adjust the axial stiffness of the (connecting arm). Therefore, the adjustment process does not require the direction of force conversion, and the adjustment is more direct and convenient, which improves the convenience of adjustment and makes it more stable and reliable. At the same time, this method uses bolt adjustment to squeeze the elastic component to change the preload to achieve adjustment. The bolt can be adjusted and twisted with a corresponding wrench tool, which is more convenient to bear force, making the adjustment process simpler, more stable and reliable.

[0009] Furthermore, the elastic member is made of rubber material (preferably TPU rubber), which has the advantages of low cost and wide elastic force adjustment range.

[0010] Furthermore, both ends of the elastic member in the axial direction are in contact with the two axially butted members at the same time. In this way, the two axially butted members can compress the elastic member, making it sufficiently flexible, and can adjust the rigidity by changing the degree of compression of the elastic member in advance.

[0011] Furthermore, the method is implemented by a bolt-based axial variable stiffness stepless adjustment device, which includes an axial docking member and a cylindrical docking member coaxially plug-fitted, the inner end of the axial docking member having a flange, and also includes a cylindrical elastic member coaxially arranged between the axial docking member and the cylindrical docking member and a preload adjustment mechanism for axial preload adjustment of the elastic member; a first inner step protruding inwardly is provided at the opening of the cylindrical docking member, and a first outer step protruding outwardly is provided on the outer surface of the axial docking member corresponding to the position of the first inner step, and a first outer step protruding outwardly is provided at the outer surface of the elastic member One end abuts against the side surfaces of the first inner step and the first outer step at the same time, and the other end abuts against the preload adjustment mechanism. The preload adjustment mechanism includes a circle of adjusting bolts axially arranged along one end of the elastic member. The inner end of the adjusting bolt abuts against the end surface of the elastic member, and the other end passes through the flange and the outer end of the cylindrical docking member to form an adjustable bolt head. The flange and the outer end of the cylindrical docking member are respectively provided with holes to cooperate with each adjusting bolt. Some adjusting bolts are threadedly screwed to the threaded holes on the flange and are clearance-matched with the sliding holes on the outer end of the cylindrical docking member. Another part of the adjusting bolts are clearance-matched with the sliding holes on the flange and are threadedly screwed to the threaded holes on the outer end of the cylindrical docking member.

[0012] In this way, when the device is used, the outer ends of the axial docking member and the cylindrical docking member are respectively connected to the connecting arm, one end of the elastic member acts on the axial docking member and the cylindrical docking member simultaneously through the first inner step and the first outer step, and the other end acts on the axial docking member and the cylindrical docking member respectively through different adjusting bolts; therefore, no matter whether the axial docking member and the cylindrical docking member are compressed or stretched in the axial direction, they will act on the elastic member in the axial direction to form extrusion, so the connecting arm can have an axial margin of activity by relying on its elastic force, forming a flexible connection in the axial direction. In this way, the axial stiffness of the connecting arm can be infinitely adjusted by only adjusting the degree of compression of the elastic member by pre-tightening the adjusting bolt, which is very convenient and more stable. At the same time, the bolt itself also realizes the anti-rotation effect between the axial docking member and the cylindrical docking member, and the structure is simpler and more ingenious.

[0013] Furthermore, a cylindrical auxiliary shell is threadedly connected to the opening of the cylindrical docking component, and the first inner step is formed on the inner ring wall of the auxiliary shell.

[0014] In this way, the forming of the first inner step is facilitated, and the assembly of the internal components is also facilitated.

[0015] Furthermore, the shaft-shaped docking member is threadedly connected with an annular threaded sleeve at a position corresponding to the auxiliary housing, the first outer step is formed on the outer side wall of the threaded sleeve, and a gap is left between the outer surface of the threaded sleeve and the inner surface of the auxiliary housing.

[0016] In this way, the forming of the first outer step is facilitated, and the assembly of the internal components is also facilitated.

[0017] Furthermore, a first hard gasket is disposed between the side surfaces of the first inner step and the first outer step and the end of the elastic component.

[0018] In this way, whether it is the force exerted by the first outer step on the end of the elastic component when under compression, or the force exerted by the first inner step on the end of the elastic component when under tension, both are transmitted to the end of the elastic component through the hard gasket, making the force more stable and balanced, avoiding the instability caused by flexural deformation caused by unilateral force on the end of the elastic component.

[0019] Furthermore, the elastic component is made of TPU rubber material.

[0020] Furthermore, in the preload adjustment mechanism, the adjusting bolts are an even number evenly distributed along the circumferential direction, half of the staggered adjusting bolts are threadedly engaged with the flange, and the other half of the adjusting bolts are threadedly engaged with the outer end of the cylindrical docking member.

[0021] In this way, the overall force of the device is more balanced and stable.

[0022] Furthermore, the inner end of each adjusting bolt abuts against the end of the elastic component through a second hard gasket.

[0023] In this way, each adjusting bolt transmits force between the second hard gasket and the elastic member, making the force more stable and balanced, thereby avoiding instability caused by folding deformation caused by unilateral force on the end of the elastic member.

[0024] Furthermore, an outer locking nut is threadedly screwed on the axial docking member at the outer side of the auxiliary shell body, and an inner locking nut is threadedly screwed on the adjacent end of the auxiliary shell body and the outer locking nut. The end of the inner locking nut facing away from the outer locking nut can abut against a boss surface protruding outward from the outer peripheral surface of the auxiliary shell body, and the adjacent ends of the outer locking nut and the inner locking nut can abut and lock each other.

[0025] In this way, the outer locking nut is locked by the inner locking nut against the boss surface on the outside of the auxiliary housing, which can better improve the locking force and obtain the self-locking effect. By locking, the connecting arm can be transformed from a flexible connection state with adjustable stiffness to a full stiffness state. Therefore, the connecting arm can be switched and controlled when it is not necessary to maintain flexibility, and it can be directly locked and converted to a full stiffness state regardless of the flexibility state of the connecting arm. It has the advantages of simple structure and convenient adjustment and switching control.

[0026] Furthermore, an axle joint is provided at the middle of the outer end of the cylindrical docking member, which extends outwards, so as to facilitate the installation and docking of the device when it is used.

[0027] In summary, the present invention has the advantages of being able to better realize the stepless adjustment of the axial stiffness of the connecting arm, making the adjustment process simpler, more stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the bolt-based axial variable stiffness stepless adjustment device used in the implementation of the present invention.

[0029] Figure 2 for Figure 1 Schematic diagram of the three-dimensional structure.

[0030] Figure 3 for Figure 1 AA section view.

[0031] Figure 4 for Figure 1 Schematic diagram of the structure when both ends of the device are under pressure.

[0032] Figure 5 for Figure 1 Schematic diagram of the structure when both ends of the device are under tension. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with specific implementation modes and accompanying drawings.

[0034] In specific implementation, a method for steplessly adjusting axial stiffness is provided, in which an elastic member is connected between two axially butted members, so that whether the two axially butted members are squeezed against each other or pulled outward along the axial direction, force transmission is achieved by squeezing the elastic member, and then the axial stiffness is adjusted by changing the axial preload of the elastic member; the method is characterized in that the preload is changed by squeezing the elastic member through a bolt axially arranged at one end of the elastic member to achieve adjustment.

[0035] In this way, this method directly relies on changing the degree of axial compression of the elastic rubber ring to change its axial preload to adjust the axial stiffness of the (connecting arm). Therefore, the adjustment process does not require the direction of force conversion, and the adjustment is more direct and convenient, which improves the convenience of adjustment and makes it more stable and reliable. At the same time, this method uses bolt adjustment to squeeze the elastic component to change the preload to achieve adjustment. The bolt can be adjusted and twisted with a corresponding wrench tool, which is more convenient to bear force, making the adjustment process simpler, more stable and reliable.

[0036] The elastic member is made of rubber material (preferably TPU rubber), which has the advantages of low cost and wide elastic force adjustment range.

[0037] The two ends of the elastic member in the axial direction are respectively in contact with the two axially butted members at the same time. In this way, the two axially butted members can compress the elastic member no matter they are mutually squeezed or pulled outward in the axial direction, so that the elastic member has sufficient flexibility, and the rigidity can be adjusted by changing the degree of compression of the elastic member in advance.

[0038] Specifically, the method is implemented by a bolt-based axial variable stiffness stepless adjustment device, the bolt-based axial variable stiffness stepless adjustment device, see Figure 1-5As shown, it comprises a shaft-shaped docking member 7 and a cylindrical docking member 13 which are coaxially plug-fitted, the inner end of the shaft-shaped docking member 7 has a flange 5, and also comprises a cylindrical elastic member 12 coaxially arranged between the shaft-shaped docking member and the cylindrical docking member and a preload adjustment mechanism for axially preloading the elastic member; the opening of the cylindrical docking member 13 is provided with a first inner step protruding inwardly, the outer surface of the shaft-shaped docking member 7 has a first outer step protruding outwardly corresponding to the position of the first inner step, one end of the elastic member 12 is in contact with the step side surfaces of the first inner step and the first outer step at the same time, and the other end of the elastic member 12 is in contact with the step side surfaces of the first inner step and the first outer step at the same time. One end is in contact with the preload adjustment mechanism, and the preload adjustment mechanism includes a circle of adjusting bolts 1 axially arranged along one end of the elastic member 12. The inner end of the adjusting bolt 1 abuts against the end face of the elastic member 12, and the other end passes through the flange 5 and the outer end of the cylindrical docking member 13 to form a bolt head for adjustment. The outer ends of the flange 5 and the cylindrical docking member 13 are respectively provided with holes to cooperate with each adjusting bolt 1. Some adjusting bolts are threadedly screwed to the threaded holes on the flange and are clearance-matched with the sliding holes on the outer end of the cylindrical docking member. Another part of the adjusting bolts are clearance-matched with the sliding holes on the flange and are threadedly screwed to the threaded holes on the outer end of the cylindrical docking member.

[0039] In this way, when the device is used, the outer ends of the axial docking member and the cylindrical docking member are respectively connected to the connecting arm, one end of the elastic member acts on the axial docking member and the cylindrical docking member simultaneously through the first inner step and the first outer step, and the other end acts on the axial docking member and the cylindrical docking member respectively through different adjusting bolts; therefore, no matter whether the axial docking member and the cylindrical docking member are compressed or stretched in the axial direction, they will act on the elastic member in the axial direction to form extrusion, so the connecting arm can have an axial margin of activity by relying on its elastic force, forming a flexible connection in the axial direction. In this way, the axial stiffness of the connecting arm can be infinitely adjusted by only adjusting the degree of compression of the elastic member by pre-tightening the adjusting bolt, which is very convenient and more stable. At the same time, the bolt itself also realizes the anti-rotation effect between the axial docking member and the cylindrical docking member, and the structure is simpler and more ingenious.

[0040] A cylindrical auxiliary housing 11 is threadedly connected to the opening of the cylindrical docking component 13 , and the first inner step is formed on the inner wall of the auxiliary housing 11 .

[0041] In this way, the forming of the first inner step is facilitated, and the assembly of the internal components is also facilitated.

[0042] Among them, the axial docking component 7 is threadedly connected with an annular threaded sleeve 10 at the position corresponding to the auxiliary shell 11, the first outer step is formed on the outer side wall of the threaded sleeve 10, and a gap is left between the outer surface of the threaded sleeve 10 and the inner surface of the auxiliary shell 11.

[0043] In this way, the forming of the first outer step is facilitated, and the assembly of the internal components is also facilitated.

[0044] A first hard gasket 14 is disposed between the side surfaces of the first inner step and the first outer step and the end of the elastic member.

[0045] In this way, whether it is the force exerted by the first outer step on the end of the elastic component when under compression, or the force exerted by the first inner step on the end of the elastic component when under tension, both are transmitted to the end of the elastic component through the hard gasket, making the force more stable and balanced, avoiding the instability caused by flexural deformation caused by unilateral force on the end of the elastic component.

[0046] Wherein, the elastic component 12 is made of TPU rubber material.

[0047] Among them, in the preload adjustment mechanism, the adjusting bolts 1 are an even number evenly distributed along the circumferential direction, half of the staggered adjusting bolts are threadedly engaged with the flange 5, and the other half of the adjusting bolts are threadedly engaged with the outer end of the cylindrical docking member.

[0048] In this way, the overall force of the device is more balanced and stable.

[0049] The inner end of each adjusting bolt 1 abuts against the end of the elastic member 12 via a second hard gasket 15 .

[0050] In this way, each adjusting bolt transmits force between the second hard gasket and the elastic member, making the force more stable and balanced, thereby avoiding instability caused by folding deformation caused by unilateral force on the end of the elastic member.

[0051] Among them, an outer locking nut 8 is threadedly screwed on the axial docking member 7 at the outer side of the sub-shell 11, and an inner locking nut 9 is threadedly screwed on the adjacent end of the sub-shell 11 and the outer locking nut 8. The end of the inner locking nut 9 facing away from the outer locking nut 8 can abut against a boss surface protruding outward from the outer peripheral surface of the sub-shell, and the adjacent ends of the outer locking nut 8 and the inner locking nut 9 can abut and lock each other.

[0052] In this way, the outer locking nut is locked by the inner locking nut against the boss surface on the outside of the auxiliary housing, which can better improve the locking force and obtain the self-locking effect. By locking, the connecting arm can be transformed from a flexible connection state with adjustable stiffness to a full stiffness state. Therefore, the connecting arm can be switched and controlled when it is not necessary to maintain flexibility, and it can be directly locked and converted to a full stiffness state regardless of the flexibility state of the connecting arm. It has the advantages of simple structure and convenient adjustment and switching control.

[0053] Among them, a shaft joint 4 is extended outwardly from the middle of the outer end of the cylindrical docking member 13. This facilitates the installation and docking of the device when it is used.

[0054] In this embodiment, there are 6 adjusting bolts. It is assumed that the bolts with even numbers, that is, the left ends of the bolts shown as the upper part in the cross-sectional view, are threadedly connected to the threaded holes on the flange, and the right ends are clearance-fitted with the sliding holes corresponding to the outer end parts of the cylindrical docking components; the bolts with odd numbers, that is, the left ends of the bolts shown as the lower part in the cross-sectional view, are clearance-fitted with the sliding holes on the flange, and the right ends are threadedly connected with the threaded holes corresponding to the outer end parts of the cylindrical docking components.

[0055] By rotating the bolt group consisting of six bolts in this way, the bolt group squeezes the second washer to the left, thereby increasing the preload force of the elastic member 7 and the axial stiffness at both ends of the device, thereby achieving stepless adjustment of the axial stiffness at both ends of the device.

[0056] When the entire device is under pressure, the elastic member is squeezed from the right end by the bolts with odd numbers, because the right ends of the bolts with odd numbers are threadedly connected to the threaded holes of the cylindrical docking member, and the left ends are clearance-matched with the sliding holes on the flange, so the bolts with odd numbers will not move to the right with the shaft-shaped docking member, but will remain stationary relative to the cylindrical docking member; while the left ends of the bolts with even numbers are threadedly connected to the flange, and the holes corresponding to the cylindrical docking member are clearance-matched, so the bolts with even numbers will move to the right with the shaft-shaped docking member. As shown in the accompanying figure description Figure 4 At this time, the force transmission path of the entire device is the shaft-shaped docking member → threaded sleeve → first hard gasket → elastic member → second hard gasket → bolts with odd numbers → tubular docking member.

[0057] When the entire device is subjected to tension, the elastic member is squeezed from the right end by the even-numbered bolts, because the right end of the even-numbered bolts has a clearance fit with the hole corresponding to the cylindrical docking member and is threadedly connected to the flange, so the even-numbered bolts move to the left together with the shaft-shaped docking member; while the left end of the odd-numbered bolts has a clearance fit with the flange and is threadedly connected to the hole corresponding to the cylindrical docking member, so the odd-numbered bolts will not move to the left together with the shaft-shaped docking member, but will remain stationary relative to the cylindrical docking member. Figure 5 At this time, the force transmission path of the entire device is the shaft-shaped docking member → bolts with even numbers → second hard gasket → elastic member → first hard gasket → auxiliary housing → cylindrical docking member.

[0058] When you want to lock the device at any position to maximize the rigidity of the entire device, you only need to rotate the inner locking nut so that the right end face of the inner locking nut is close to the left end face of the threaded sleeve, and then rotate the outer locking nut so that the right end face of the outer locking nut is close to the left end face of the inner locking nut, so that the shell and the axial docking component cannot move axially relative to each other. At this time, the axial rigidity of both ends of the device is maximum.

[0059] Therefore, the present invention has the following beneficial effects: 1 Compared with other variable stiffness joints, the present invention has a larger stiffness adjustment range and the ability of infinite stiffness adjustment; 2 Compared with other variable stiffness joints, the present invention can lock the entire device at any position of the device's telescopic deformation, and the stiffness reaches the maximum, unlike similar related inventions that can only reset to a specified unique position to lock the device; 3 Compared with the applicant's prior patent scheme described in the background technology, the present application uses bolts to adjust the stiffness, which is not only more convenient to adjust with a special wrench; and when one of the bolt connections fails, it can also work normally relying on the remaining normally connected bolts, with better reliability; 4 The present invention has a simple and compact structure and low processing and manufacturing costs; 5 The present invention has a high degree of modularization of parts and components, convenient maintenance, and good economy.

Claims

1. A method for infinitely adjusting axial stiffness, wherein an elastic member is connected between two axially butted members, so that the two axially butted members can achieve force transmission by squeezing the elastic member when they are mutually squeezed or pulled outward in the axial direction, and then the axial stiffness can be adjusted by changing the axial preload of the elastic member; characterized in that: The adjustment is achieved by compressing the elastic member with a bolt axially arranged at one end of the elastic member to change its pre-tightening force.

2. The method for steplessly adjusting axial stiffness according to claim 1, characterized in that: The elastic component is made of rubber material.

3. The method for steplessly adjusting axial stiffness according to claim 1, characterized in that: Both ends of the elastic component along the axial direction are in abutment with two axial docking components respectively and simultaneously.

4. The method for steplessly adjusting axial stiffness according to claim 1, characterized in that: The method is implemented by a bolt-based axial variable stiffness stepless adjustment device, which includes a shaft-shaped docking member and a cylindrical docking member coaxially plug-in-matched, the inner end of the shaft-shaped docking member has a flange, and also includes a cylindrical elastic member coaxially arranged between the shaft-shaped docking member and the cylindrical docking member and a preload adjustment mechanism for axial preload adjustment of the elastic member; the opening of the cylindrical docking member is provided with a first inner step protruding inwardly, the outer surface of the shaft-shaped docking member has a first outer step protruding outwardly corresponding to the position of the first inner step, and one end of the elastic member is coaxially arranged between the shaft-shaped docking member and the cylindrical docking member. The first end of the adjusting bolt abuts against the side surfaces of the first inner step and the first outer step, and the other end abuts against the preload adjustment mechanism. The preload adjustment mechanism includes a circle of adjusting bolts axially arranged along one end of the elastic member. The inner end of the adjusting bolt abuts against the end surface of the elastic member, and the other end passes through the flange and the outer end of the cylindrical docking member to form a bolt head for adjustment. The flange and the outer end of the cylindrical docking member are respectively provided with holes to cooperate with each adjusting bolt. Some of the adjusting bolts are threadedly screwed to cooperate with the threaded holes on the flange and are clearance-matched with the sliding holes on the outer end of the cylindrical docking member. Another part of the adjusting bolts are clearance-matched with the sliding holes on the flange and are threadedly screwed to cooperate with the threaded holes on the outer end of the cylindrical docking member.

5. The method for steplessly adjusting axial stiffness according to claim 4, characterized in that: A cylindrical auxiliary housing is threadedly connected to the opening of the cylindrical docking component, and the first inner step is formed on the inner wall of the auxiliary housing.

6. The method for steplessly adjusting axial stiffness according to claim 5, characterized in that: The shaft-shaped docking member is threadedly connected with an annular threaded sleeve at a position corresponding to the auxiliary housing, the first outer step is formed on the outer side wall of the threaded sleeve, and a gap is left between the outer surface of the threaded sleeve and the inner surface of the auxiliary housing.

7. The method for steplessly adjusting axial stiffness according to claim 6, characterized in that: A first hard gasket is also disposed between the side surfaces of the first inner step and the first outer step and the end of the elastic member; The elastic component is made of TPU rubber material.

8. The method for steplessly adjusting axial stiffness according to claim 4, characterized in that: In the preload adjustment mechanism, the adjusting bolts are an even number evenly distributed along the circumferential direction, half of the staggered adjusting bolts are threadedly engaged with the flange, and the other half of the adjusting bolts are threadedly engaged with the outer end of the cylindrical docking member.

9. The method for steplessly adjusting axial stiffness according to claim 8, characterized in that: The inner end of each adjusting bolt is butted against the end of the elastic component through a second hard washer.

10. The method for steplessly adjusting axial stiffness according to claim 4, characterized in that: The shaft-shaped docking component is also threadedly provided with an outer locking nut at the outer side of the auxiliary shell body, and an inner locking nut is also threadedly provided at the adjacent end of the auxiliary shell body and the outer locking nut. The end of the inner locking nut facing away from the outer locking nut can abut against a boss surface protruding outward from the outer peripheral surface of the auxiliary shell body, and the adjacent ends of the outer locking nut and the inner locking nut can abut and lock each other.

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