Axial rigidity adjusting method of connecting arm

Abstract

The invention discloses a method for adjusting the axial rigidity of a connecting arm, which is characterized in that an elastic cylindrical component is connected between two axial butt-joint components, so that force transmission is realized by extruding the elastic cylindrical component no matter the two axial butt-joint components are mutually extruded and mutually pulled outwards in the axial direction, and the axial rigidity of the connecting arm is adjusted. And then the axial rigidity of the connecting arm is adjusted by changing the pretightening force of the elastic rubber ring in the axial direction. Stepless adjustment of the axial rigidity of the connecting arm can be better achieved, meanwhile, adjustment convenience is improved, and direct switching control of the connecting arm from flexibility to full rigidity can be achieved; the device has the advantages of convenience in adjustment, large adjustable range, better stability and the like.

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 adjusting the axial stiffness of a connecting arm. 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] In order to solve the above problems, the applicant has applied for patent CN202310327105.7, which discloses a linear variable stiffness joint, including a first connecting plate and a second connecting plate coaxially arranged opposite to each other, and its characteristics are that a connecting shaft is axially arranged at one end of the first connecting plate facing the second connecting plate, and a plurality of spiral abutment springs are evenly distributed along the circumference at the outer end of the connecting shaft, the abutment springs are arranged along the diameter direction and the inner end abuts on the connecting shaft, and the outer end is connected to the second connecting plate through a force adjustment mechanism. The joint of this invention can adjust the axial stiffness, but it needs to rely on a mechanism to convert the axial force into radial force during adjustment, and still has defects such as a relatively complex structure, limited adjustment effect, and high cost.

[0005] Therefore, how to design a variable stiffness adjustment method that can better achieve stepless adjustment of the axial stiffness of the connecting arm while improving the convenience and stability of adjustment has become a problem that technical personnel in this field need to consider and solve. Summary of the invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is: how to provide a method for adjusting the axial stiffness of the connecting arm that can better achieve stepless adjustment of the axial stiffness of the connecting arm while improving the convenience and stability of adjustment.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for adjusting the axial stiffness of a connecting arm is characterized in that an elastic cylindrical member is connected between two axially butted members, so that whether the two axially butted members are squeezed or pulled outwardly in the axial direction, force transmission is achieved by squeezing the elastic cylindrical member, and then the axial stiffness of the connecting arm is adjusted by changing the axial preload of the elastic rubber ring.

[0008] In this way, the method directly relies on changing the degree of axial compression of the elastic rubber ring and changing its axial preload to adjust the axial stiffness of the connecting arm. Therefore, the adjustment process does not require force direction conversion, and the adjustment is more direct and convenient, which improves the convenience of adjustment and makes it more stable and reliable.

[0009] Furthermore, the elastic cylindrical 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 cylindrical 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 cylindrical member, generate sufficient flexibility, and adjust the rigidity by changing the degree of compression of the elastic cylindrical member in advance, whether they are pressed against each other or pulled outwards in the axial direction.

[0011] Furthermore, the method is implemented by an axial stiffness adjustment device for a connecting arm, the axial stiffness adjustment device for the connecting arm comprising an axial docking member and a cylindrical docking member coaxially plug-fitted, and also comprising an elastic cylindrical member coaxially arranged between the axial docking member and the cylindrical docking member and a preload adjustment mechanism for axially preloading the elastic cylindrical member; the opening of the cylindrical docking member comprises a first inner step protruding inwardly, the outer surface of the axial docking member corresponding to the position of the first inner step comprises a first outer step protruding outwardly, the inner wall of the cylindrical docking member is provided with an inwardly protruding second inner step at a distance from the first inner step, and the outer surface of the axial docking member corresponds to the position of the second inner step comprises a second outer step protruding outwardly; one end of the elastic cylindrical member is simultaneously in contact with the step side surfaces of the first inner step and the second outer step, and the other end is in contact with the preload adjustment mechanism, and the other end of the preload adjustment mechanism is simultaneously in contact with the step side surfaces of the second inner step and the second outer step; a clearance window is also provided on the cylindrical docking member, and the preload adjustment mechanism is exposed from the clearance window.

[0012] In this way, when the device is used, the outer ends of the shaft-shaped docking member and the cylindrical docking member are respectively connected to the connecting arm. Regardless of whether the shaft-shaped docking member and the cylindrical docking member are compressed or pulled in the axial direction, they will act on the elastic cylindrical member in the axial direction to form extrusion, so that 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, it is only necessary to adjust the compression degree of the elastic cylindrical member in advance through the pre-tightening adjustment mechanism to achieve stepless adjustment of the axial stiffness of the connecting arm, which is very convenient and has higher stability.

[0013] Furthermore, an annular connector is threadedly connected to the opening of the cylindrical docking component, and the first inner step is formed on the inner wall of the connector.

[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 collar corresponding to the position of the connector, the first outer step is formed on the outer side wall of the collar, and a gap is left between the outer surface of the collar and the inner surface of the connector.

[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 hard gasket is disposed between the side surfaces of the first inner step and the first outer step and the end of the elastic cylindrical member.

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

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

[0020] Furthermore, the preload adjustment mechanism includes a stiffness adjustment ring which is located on the inner side and is in the shape of a cylinder as a whole. The stiffness adjustment ring is sleeved on the axial docking member and a flat key is arranged between the stiffness adjustment ring and the axial docking member to achieve a non-rotational fit. A space is reserved between the keyway and the flat key of the stiffness adjustment ring for the stiffness adjustment ring to slide axially. The outer surface of the stiffness adjustment ring has an outwardly protruding abutment step. One side of the abutment step abuts against the end of the elastic cylindrical member. The outer surface of the other side of the abutment step is provided with an external thread and is threadedly screwed with a stiffness adjustment nut. The end of the stiffness adjustment nut facing away from the abutment step abuts against the side surfaces of the second inner step and the second outer step at the same time. The outer surface of the stiffness adjustment nut is exposed in the clearance window.

[0021] In this way, the axial distance between the rigidity adjusting nut and the rigidity adjusting ring can be easily adjusted by rotating the rigidity adjusting nut, and the axial preload force of the elastic cylindrical member can be adjusted through the rigidity adjusting ring. The structure is ingenious, simple and reliable.

[0022] Furthermore, a stop pin is provided on the shaft-shaped docking component in a radially fixed outer protrusion, and the outer end of the stop pin can be axially slidably fitted in an axially sliding groove on the inner wall of the cylindrical docking component.

[0023] In this way, mutual rotation between the shaft-shaped abutting member and the cylindrical abutting member can be avoided.

[0024] Furthermore, a first locking nut is threadedly provided on the axial docking component at a position outside the connecting head, and the first locking nut has an abutting end for abutting against the outer side surface of the connecting head to achieve locking. A second locking nut is threadedly provided on the axial docking component at a position on the side of the second inner step away from the elastic cylindrical component, and the second locking nut has an abutting end for abutting against the step surface on the side of the second inner step away from the elastic cylindrical component to achieve locking, and the outer surface of the second locking nut is exposed in the said yield window.

[0025] In this way, the two locking nuts can be simultaneously abutted against the connector and the second inner step to achieve locking. The connecting arm is changed from a flexible connection state with adjustable stiffness to a full stiffness state by using the principle of holding the two ends tightly. Therefore, the connecting arm can be switched and controlled when it is not necessary to maintain flexibility, and can be directly locked and converted to a full stiffness state regardless of the flexibility of the connecting arm. It has the advantages of simple structure and convenient adjustment and switching control.

[0026] To sum up, the present 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, and better stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the connecting arm axial stiffness adjustment device used in the implementation of the present invention.

[0028] Figure 2 for Figure 1 sectional view of .

[0029] Figure 3 for Figure 2 Schematic diagram of the structure when both ends of the device are under tension.

[0030] Figure 4 for Figure 2 Schematic diagram of the structure when both ends of the device are under pressure. DETAILED DESCRIPTION

[0031] In specific implementation, a method for adjusting the axial stiffness of a connecting arm is characterized in that an elastic cylindrical member is connected between two axially butted components, so that whether the two axially butted components are squeezed or pulled outward along the axial direction, force transmission is achieved by squeezing the elastic cylindrical member, and then the axial stiffness of the connecting arm is adjusted by changing the axial preload of the elastic rubber ring.

[0032] In this way, the method directly relies on changing the degree of axial compression of the elastic rubber ring and changing its axial preload to adjust the axial stiffness of the connecting arm. Therefore, the adjustment process does not require force direction conversion, and the adjustment is more direct and convenient, which improves the convenience of adjustment and makes it more stable and reliable.

[0033] In practice, the elastic cylindrical member is made of rubber material (preferably TPU rubber), which has the advantages of low cost and wide elastic force adjustment range.

[0034] During implementation, both ends of the elastic cylindrical member in the axial direction are in contact with the two axially butted members at the same time. In this way, no matter the two axially butted members are mutually squeezed or pulled outward in the axial direction, the elastic cylindrical member can be compressed to produce sufficient flexibility, and the rigidity can be adjusted by changing the degree of compression of the elastic cylindrical member in advance.

[0035] In practice, the method is implemented by a connecting arm axial stiffness adjustment device, see Figure 1-4 As shown, the connecting arm axial stiffness adjustment device comprises an axial docking member 1 and a cylindrical docking member 10 which are coaxially plug-fitted, and also comprises an elastic cylindrical member 6 which is coaxially arranged between the axial docking member and the cylindrical docking member, and a preload adjustment mechanism for realizing axial preload of the elastic cylindrical member; the opening of the cylindrical docking member 10 has a first inner step protruding inwardly, the outer surface of the axial docking member has a first outer step protruding outwardly corresponding to the position of the first inner step, the inner wall of the cylindrical docking member is provided with an inwardly protruding second inner step at a distance from the first inner step, and the outer surface of the axial docking member has a second outer step protruding outwardly corresponding to the position of the second inner step; one end of the elastic cylindrical member is simultaneously in contact with the step side surfaces of the first inner step and the second outer step, and the other end is in contact with the preload adjustment mechanism, and the other end of the preload adjustment mechanism is simultaneously in contact with the step side surfaces of the second inner step and the second outer step; a clearance window is also provided on the cylindrical docking member, and the preload adjustment mechanism is exposed from the clearance window.

[0036] In this way, when the device is used, the outer ends of the shaft-shaped docking member and the cylindrical docking member are respectively connected to the connecting arm. Regardless of whether the shaft-shaped docking member and the cylindrical docking member are compressed or pulled in the axial direction, they will act on the elastic cylindrical member in the axial direction to form extrusion, so that 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, it is only necessary to adjust the compression degree of the elastic cylindrical member in advance through the pre-tightening adjustment mechanism to achieve stepless adjustment of the axial stiffness of the connecting arm, which is very convenient and has higher stability.

[0037] Wherein, an annular connector 4 is threadedly connected to the opening of the cylindrical docking component, and the first inner step is formed on the inner wall of the connector 4.

[0038] In this way, the forming of the first inner step is facilitated, and the assembly of the internal components is also facilitated.

[0039] Among them, the shaft-shaped docking component is threadedly connected with an annular ring 3 at the position corresponding to the connector, the first outer step is formed on the outer side wall of the ring 3, and a gap is left between the outer surface of the ring and the inner surface of the connector.

[0040] In this way, the forming of the first outer step is facilitated, and the assembly of the internal components is also facilitated.

[0041] A hard gasket 5 is also disposed between the side surfaces of the first inner step and the first outer step and the end of the elastic cylindrical member.

[0042] In this way, whether it is the force exerted by the first outer step on the end of the elastic cylindrical component when under pressure, or the force exerted by the first inner step on the end of the elastic cylindrical component when under tension, both are transmitted to the end of the elastic cylindrical component through the hard gasket, making the force more stable and balanced, avoiding the instability caused by folding deformation due to unilateral force on the end of the elastic cylindrical component.

[0043] Wherein, the elastic cylindrical member 6 is made of TPU rubber material.

[0044] Among them, the preload adjustment mechanism includes a stiffness adjustment ring 7 which is located on the inner side and is in the shape of a cylinder as a whole. The stiffness adjustment ring 7 is sleeved on the axial docking component 1 and a flat key 11 is provided between the stiffness adjustment ring 7 to achieve a rotation-proof fit. A space is reserved between the keyway of the stiffness adjustment ring 7 and the flat key 11 for the stiffness adjustment ring to slide axially. The outer surface of the stiffness adjustment ring 7 has an outwardly convex abutment step. One side of the abutment step abuts against the end of the elastic cylindrical component. The outer surface of the other side of the abutment step is provided with an external thread and is threadedly screwed with a stiffness adjustment nut 8. The end of the stiffness adjustment nut 8 which is away from the abutment step abuts against the side surfaces of the second inner step and the second outer step at the same time. The outer surface of the stiffness adjustment nut 8 is exposed in the clearance window.

[0045] In this way, the axial distance between the rigidity adjusting nut and the rigidity adjusting ring can be easily adjusted by rotating the rigidity adjusting nut, and the axial preload force of the elastic cylindrical member can be adjusted through the rigidity adjusting ring. The structure is ingenious, simple and reliable.

[0046] Among them, a stop pin 12 is radially fixedly protruded on the axial docking component 1, and the outer end of the stop pin 12 can be axially slidably fitted in an axial sliding groove (not shown in the figure) on the inner wall of the cylindrical docking component 10.

[0047] In this way, mutual rotation between the shaft-shaped abutting member and the cylindrical abutting member can be avoided.

[0048] Among them, a first locking nut 2 is threadedly provided on the axial docking component at the outer side of the connecting head, and the first locking nut 2 has an abutting end for abutting with the outer side surface of the connecting head to achieve locking. A second locking nut 9 is threadedly provided on the axial docking component at a position on the side of the second inner step away from the elastic cylindrical component. The second locking nut 9 has an abutting end for abutting with the step surface on the side of the second inner step away from the elastic cylindrical component to achieve locking, and the outer surface of the second locking nut 9 is exposed in the said yield window.

[0049] In this way, the two locking nuts can be simultaneously abutted against the connector and the second inner step to achieve locking. The connecting arm is changed from a flexible connection state with adjustable stiffness to a full stiffness state by using the principle of holding the two ends tightly. Therefore, the connecting arm can be switched and controlled when it is not necessary to maintain flexibility, and can be directly locked and converted to a full stiffness state regardless of the flexibility of the connecting arm. It has the advantages of simple structure and convenient adjustment and switching control.

[0050] 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 be reset to a specified unique position to lock the device; 3. The present invention adopts manual rotation of the stiffness to adjust the nut joint stiffness, thereby reducing the number of drives, while traditional mechanisms often use motor active drive, which increases the drive cost and is not convenient for practical use; 4. The present invention has a simple and compact structure and a low processing and manufacturing cost; 5. The present invention has a high degree of modularization of parts and components, convenient maintenance, and good economy.

Claims

1. A method for adjusting the axial stiffness of a connecting arm, characterized in that: An elastic cylindrical member is connected between the two axial butt joint members installed on the connecting arm, so that no matter the two axial butt joint members are squeezed or pulled outward in the axial direction, the force transmission is achieved by squeezing the elastic cylindrical member, and then the axial stiffness of the connecting arm is adjusted by changing the axial preload of the elastic rubber ring.

2. The method for adjusting the axial stiffness of a connecting arm according to claim 1, characterized in that: The elastic cylindrical member is made of rubber material.

3. The method for adjusting the axial stiffness of a connecting arm according to claim 1, characterized in that: Both ends of the elastic cylindrical member along the axial direction are in abutment with two axial docking members respectively and simultaneously.

4. The method for adjusting the axial stiffness of a connecting arm according to claim 3, characterized in that: The method is implemented by an axial stiffness adjustment device for a connecting arm, the axial stiffness adjustment device for the connecting arm comprises an axial docking member and a cylindrical docking member coaxially plug-fitted, and also comprises an elastic cylindrical member coaxially arranged between the axial docking member and the cylindrical docking member and a pre-tightening adjustment mechanism for axially pre-tightening the elastic cylindrical member; the opening of the cylindrical docking member comprises a first inner step protruding inwardly, the outer surface of the axial docking member corresponds to the position of the first inner step and comprises a first outer step protruding outwardly, the inner wall of the cylindrical docking member is provided with an inwardly protruding second inner step at a distance from the first inner step, and the outer surface of the axial docking member corresponds to the position of the second inner step and comprises a second outer step protruding outwardly; one end of the elastic cylindrical member abuts against the step side surfaces of the first inner step and the second outer step at the same time, and the other end abuts against the pre-tightening adjustment mechanism, and the other end of the pre-tightening adjustment mechanism abuts against the step side surfaces of the second inner step and the second outer step at the same time; a clearance window is also provided on the cylindrical docking member, and the pre-tightening adjustment mechanism is exposed from the clearance window.

5. The method for adjusting the axial stiffness of a connecting arm according to claim 4, characterized in that: An annular connector is threadedly connected to the opening of the cylindrical docking component, and the first inner step is formed on the inner wall of the connector.

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

7. The method for adjusting the axial stiffness of a connecting arm according to claim 6, characterized in that: A 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 cylindrical member.

8. The method for adjusting the axial stiffness of a connecting arm according to claim 6, characterized in that: The preload adjustment mechanism includes a stiffness adjustment ring which is located on the inner side and is in a cylindrical shape as a whole. The stiffness adjustment ring is sleeved on the axial docking component and is anti-rotationally fitted with the axial docking component through a flat key. A space is reserved between the keyway and the flat key of the stiffness adjustment ring for the stiffness adjustment ring to slide axially. The outer surface of the stiffness adjustment ring has an outwardly convex abutment step. One side of the abutment step abuts against the end of the elastic cylindrical component. The outer surface of the other side of the abutment step is provided with an external thread and is threadedly screwed with a stiffness adjustment nut. The end of the stiffness adjustment nut facing away from the abutment step abuts against the side surfaces of the second inner step and the second outer step at the same time, and the outer surface of the stiffness adjustment nut is exposed in the clearance window.

9. The method for adjusting the axial stiffness of a connecting arm according to claim 6, characterized in that: A stop pin is fixedly protruded radially on the shaft-shaped docking component, and the outer end of the stop pin can be axially slidably fitted in an axial sliding groove on the inner wall of the cylindrical docking component.

10. The method for adjusting the axial stiffness of a connecting arm according to claim 6, characterized in that: The axial docking component is also threadedly provided with a first locking nut at the outer side of the connecting head, and the first locking nut has an abutting end for abutting against the outer side surface of the connecting head to achieve locking. The axial docking component is also threadedly provided with a second locking nut at a position on the side of the second inner step away from the elastic cylindrical component, and the second locking nut has an abutting end for abutting against the step surface on the side of the second inner step away from the elastic cylindrical component to achieve locking, and the outer surface of the second locking nut is exposed in the said yield window.

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