Constant force structure that reduces the distance between elastic elements

Abstract

This utility model discloses a constant force structure that reduces the distance of the elastic element. The arm body, rotating head seat, support plate, and adjustment seat are sequentially hinged to form a parallel four-bar structure. The elastic component includes a first connecting piece, a second connecting piece, and an elastic element that can elastically extend and retract. The lower end of the first connecting piece is hinged to the connecting hole of the support plate, and the upper end of the first connecting piece is hinged to the rear end of the second connecting piece through a sixth horizontal rotating shaft. The sixth horizontal rotating shaft is slidably inserted into a long strip-shaped arm slide groove on the front side wall of the arm body. The front end of the second connecting piece is hinged to the arm positioning hole on the front side wall of the arm body. The front end of the elastic element is hinged to the middle of the first connecting piece, and the rear end of the elastic element is installed on the adjustment seat, the arm body, or the hinge shaft of the two. This utility model can effectively reduce the micro-adjustment distance of the elastic element in the arm, allowing it to better achieve the constant force output state of the spring and improve the stability after the display height is adjusted.

Description

Technical Field

[0001] This utility model relates to a monitor bracket, and more particularly to a constant force structure that reduces the distance between elastic elements. Background Technology

[0002] Monitors are used in many places, such as homes, offices, and public places, and are often mounted on monitor stands.

[0003] Traditional monitor height and horizontal rotation adjustment relies on plastic pads clamped between the arm and the main body, using friction to achieve this. However, these plastic pads are easily worn and damaged during long-term use, resulting in poor stability after the monitor height and horizontal rotation adjustment. It is difficult to maintain stable support and position over a long period of time. Furthermore, adjustment often requires tightening or loosening screws, which is cumbersome. Influenced by the friction value, the monitor has a small load-bearing capacity, and assembly is complicated.

[0004] Currently, some monitor stands have elastic components installed inside, using the elastic force of these components to support the monitor. In existing structures that use elastic components to support the monitor, the springs of these components are directly fixed to the rotating head. When the arm moves up and down, the springs inside the arm will stretch differently depending on the position, making it impossible to achieve the optimal constant force state. This can lead to the monitor slipping up and bouncing down under load. Summary of the Invention

[0005] To overcome the above-mentioned defects, this utility model provides a constant force structure that reduces the distance between elastic elements. This constant force structure that reduces the distance between elastic elements can better achieve the constant force output state of the spring during the lifting and lowering of the arm.

[0006] The technical solution adopted by this utility model to solve its technical problem is as follows: a constant force structure for reducing the distance of elastic components, including an adjusting seat, a rotating head seat, an arm body, a support plate, and an elastic component. The front and rear ends of the arm body are respectively rotatable around a first horizontal rotating axis and a second horizontal rotating axis and are installed on the upper ends of the rotating head seat and the adjusting seat. The front and rear ends of the support plate are respectively rotatable around a third horizontal rotating axis and a fourth horizontal rotating axis and are installed on the lower ends of the rotating head seat and the adjusting seat. The adjusting seat, the arm body, the rotating head seat, and the support plate together form a parallel four-bar linkage structure. The front side wall of the support plate is provided with a support plate connecting hole and a support plate arc-shaped hole, and the support plate arc-shaped hole and the support plate connecting hole are concentrically arranged. The front side wall of the arm body is provided with an arm... The arm has a positioning hole and a long, narrow arm groove. The elastic component includes a first connecting piece, a second connecting piece, and an elastic element that can stretch and contract. The lower end of the first connecting piece is hinged to the support plate connecting hole via a fifth horizontal pivot. The upper end of the first connecting piece is hinged to the rear end of the second connecting piece via a sixth horizontal pivot. The sixth horizontal pivot is slidably inserted into the long, narrow arm groove on the front side wall of the arm body. The front end of the second connecting piece is hinged to the arm positioning hole on the front side wall of the arm body via a seventh horizontal pivot. The front end of the elastic element is hinged to the middle of the first connecting piece via an eighth horizontal pivot. The rear end of the elastic element is mounted on the second horizontal pivot, an adjusting seat, or the inner side wall of the rear end of the arm body.

[0007] As a further improvement of this utility model, a cavity structure is formed on the inner side of the arm body, and the support plate and elastic component are both accommodated in the cavity structure of the arm body. The front end and rear end of the arm body are respectively formed with clearance notches. The rotating head seat and the adjusting seat can be rotatably inserted into the cavity structure of the arm body through the clearance notches. The arm positioning hole and the arm sliding groove are provided on the inner sidewalls of the left and right sides of the arm body.

[0008] As a further improvement of this utility model, the arm groove is an inverted U-shaped open groove with an open bottom or a closed long groove.

[0009] As a further improvement of this utility model, the elastic element includes a spring, an adjusting bolt, and a connecting block. A hook is formed at the front end of the spring, and the hook is sleeved on the outside of the eighth horizontal rotating shaft. The connecting block is fixedly installed on the rear end of the spring. The stud of the adjusting bolt is movably screwed to the connecting block. The stud of the adjusting bolt can be extended and retracted to be accommodated in the inner ring of the spring. A bolt through hole extending radially is provided on the second horizontal rotating shaft. The adjusting bolt passes through the bolt through hole, and the head of the adjusting bolt stops at the rear side of the outer circumference of the second horizontal rotating shaft. An avoidance adjustment hole is formed at the rear end of the arm body, which is directly opposite the head of the adjusting bolt. Hardware tools can be inserted into the arm body through the avoidance adjustment hole and rotate the adjusting bolt. Rotating the adjusting bolt can change the initial elastic force value of the elastic element.

[0010] As a further improvement of this utility model, a flat-bottomed groove with a descaling structure is provided on the rear side wall of the second horizontal rotating shaft in the circumferential direction. The head of the adjusting bolt is accommodated in the flat-bottomed groove, and the head of the adjusting bolt is tightly abutted against the flat bottom of the flat-bottomed groove.

[0011] As a further improvement of this utility model, the upper end of the adjustment seat forms a U-shaped structure, and the two side walls of the U-shaped structure of the adjustment seat are respectively provided with first horizontal hinge holes. The rear end of the arm body is sleeved on the outside of the U-shaped structure at the upper end of the adjustment seat. The two side walls of the rear end of the arm body are respectively provided with second horizontal hinge holes. The second horizontal rotating shaft includes an adjusting bolt limiting shaft and connecting screws. The bolt through hole is located in the middle part of the adjusting bolt limiting shaft. The two ends of the adjusting bolt limiting shaft are respectively inserted into the first horizontal hinge hole and the second horizontal hinge hole. The two connecting screws pass through the second horizontal hinge hole and the first horizontal hinge hole respectively and are screwed to the two ends of the adjusting bolt limiting shaft. The heads of the two connecting screws are respectively pressed against the left and right side surfaces of the rear end of the arm body.

[0012] As a further improvement of this utility model, the bottom surface of the U-shaped structure on the adjusting seat is a pointed bottom structure with a middle height higher than the front and rear sides, and the screw part and head of the adjusting bolt are respectively stopped on the front and rear sides of the bottom surface of the U-shaped structure on the adjusting seat.

[0013] As a further improvement of this utility model, the first connecting piece, the second connecting piece, and the support plate are all U-shaped structures. The support plate is sleeved on the outer side of the lower end of the first connecting piece, and the rear end of the second connecting piece is sleeved on the outer side of the upper end of the first connecting piece. The elastic element is accommodated inside the U-shaped structure of the support plate, and the front end of the elastic element extends into the inner side of the first connecting piece. The rotating head seat has stepped surfaces formed on both axial side walls for de-thinning. The front end of the second connecting piece and the front end of the support plate are both sleeved on the outer side of the thinned stepped surfaces of the rotating head seat.

[0014] As a further improvement of this utility model, the arm body is also provided with an adjusting bolt guide plate, an opening groove is formed on the adjusting bolt guide plate, the adjusting bolt passes through the opening groove, and the bottom surface of the opening groove stops on the upper side surface of the adjusting bolt.

[0015] The beneficial effects of this utility model are: the tension point of the elastic element of this utility model is through the first connecting piece and the second connecting piece, and the force value is applied to the support plate; when the arm is raised and lowered through the first connecting piece and the second connecting piece, the micro-adjustment distance of the elastic element in the arm can be effectively reduced, so that it can better achieve the constant force output state of the spring and improve the stability of the display after the height is adjusted. Attached Figure Description

[0016] Figure 1 This is an exploded perspective view of the present invention;

[0017] Figure 2 This is a perspective view of the elastic component of the present invention;

[0018] Figure 3 This is a front view of the elastic component of the present invention;

[0019] Figure 4 This is a top view of the elastic component of the present invention;

[0020] Figure 5 for Figure 4 Sectional view along line AA;

[0021] Figure 6 This is a perspective view of the first connecting piece of the present invention;

[0022] Figure 7 This is a perspective view of the second connecting piece of the present invention;

[0023] Figure 8 This is a front view of the support plate of the present invention;

[0024] Figure 9 This is a front view of the right arm cover of the present invention;

[0025] Figure 10 This is a perspective view of the rotating head seat of the present invention;

[0026] Figure 11 This is a perspective view of the adjustment seat of the present invention;

[0027] Figure 12 This is a perspective view of the adjusting bolt limiting shaft of the present invention;

[0028] Figure 13 This is a front view of the invention from a low angle;

[0029] Figure 14 This is a top view of the invention from a low angle.

[0030] Figure 15 for Figure 14 Sectional view along the BB direction;

[0031] Figure 16 for Figure 15 C-axis sectional view;

[0032] Figure 17 This is a top view of the invention.

[0033] Figure 18 This is a top view of the present invention.

[0034] Figure 19 for Figure 18 Sectional view along the DD direction;

[0035] Figure 20 This is a front view of the invention from a head-up perspective. Detailed Implementation

[0036] Example: A constant force structure for reducing the distance between elastic components includes an adjusting seat 1, a rotating head seat 2, an arm body 3, a support plate 4, and an elastic component 5. The front and rear ends of the arm body 3 are respectively rotatable around a first horizontal rotating axis 6 and a second horizontal rotating axis and are mounted on the upper ends of the rotating head seat 2 and the adjusting seat 1. The front and rear ends of the support plate 4 are respectively rotatable around a third horizontal rotating axis 7 and a fourth horizontal rotating axis 8 and are mounted on the lower ends of the rotating head seat 2 and the adjusting seat 1. The adjusting seat 1, the arm body 3, the rotating head seat 2, and the support plate 4 together form a parallel four-bar linkage structure. The front side wall of the support plate 4 is provided with a support plate connecting hole 9 and a support plate arc-shaped hole 10, and the support plate arc-shaped hole 10 and the support plate connecting hole 9 are concentrically arranged. The front side wall of the arm body 3 is provided with an arm positioning hole 11 and a long strip-shaped arm sliding groove 1. 2. The elastic component 5 includes a first connecting piece 13, a second connecting piece 14, and an elastic element capable of elastic extension and retraction. The lower end of the first connecting piece 13 is hinged to the support plate connecting hole 9 via a fifth horizontal pivot 15. The upper end of the first connecting piece 13 is hinged to the rear end of the second connecting piece 14 via a sixth horizontal pivot 16. The sixth horizontal pivot 16 is slidably inserted into the elongated arm slide groove 12 on the front side wall of the arm body 3. The front end of the second connecting piece 14 is hinged to the arm positioning hole 11 on the front side wall of the arm body 3 via a seventh horizontal pivot 17. The front end of the elastic element is hinged to the middle of the first connecting piece 13 via an eighth horizontal pivot 18. The rear end of the elastic element is installed on the second horizontal pivot, the adjusting seat 1, or the inner side wall of the rear end of the arm body 3.

[0037] When adjusting the monitor height, due to the parallel four-bar linkage structure formed by the arm body 3, adjustment seat 1, support plate 4, and rotating head, only the arm body 3 needs to be rotated to cause the rotating head seat 2 to move up and down without rotating. This allows the monitor to be adjusted only in height without affecting its tilt angle. When the arm moves up and down, the first connecting piece 13 and the second connecting piece 14 rotate synchronously. The second connecting piece 14 rotates around the seventh horizontal pivot 17, and the first connecting piece 13 rotates around the fifth horizontal pivot 15. Simultaneously, the first connecting piece 13 swings synchronously with the support plate 4, and the second connecting piece 14 swings synchronously with the arm body 3. The eighth horizontal pivot 18 on the first connecting piece 13 moves a small distance within the arc-shaped hole 10 of the support plate.

[0038] The front end of the elastic element moves synchronously with the eighth horizontal rotating shaft 18 as the arm moves up and down, displacing within the arc-shaped hole 10 of the support plate 4. This causes the elastic element to produce a slight extension and retraction movement. The first connecting piece 13 causes the elastic element to extend and retract, changing its tension value. The tension point of the elastic element applies its force to the support plate 4 through the first connecting piece 13 and the second connecting piece 14. This structure can reduce the extension and retraction adjustment distance of the elastic element during the up and down swing adjustment of the arm body 3, making it easier to achieve a constant force output state.

[0039] This allows the head-mounted display to maintain a stable up-and-down hovering state under the constant force within the force range of the arm body 3 after the display is suspended, thus avoiding the phenomenon of falling up or bouncing down.

[0040] The inner side of the arm body 3 forms a cavity structure, and the support plate 4 and the elastic component 5 are both accommodated in the cavity structure of the arm body 3. The front end and rear end of the arm body 3 are respectively formed with clearance notches. The rotating head seat 2 and the adjusting seat 1 can be rotatably inserted into the cavity structure of the arm body 3 through the clearance notches. The arm positioning hole 11 and the arm sliding groove 12 are provided on the inner sidewalls of the left and right sides of the arm body 3.

[0041] The above structure hides all the hinge joints of the parallelogram within the hollow structure of the arm body 3, which improves the overall aesthetics and protects the hinge joints. The arm body 3 can be designed as a joint structure consisting of a left arm cover 31 with a U-shaped cross-section and a right arm cover 32 with a U-shaped cross-section, which together form a hollow cavity structure. The arm body 3 is designed as a plug-in splicing structure, which facilitates the assembly of the elastic component 5 and the support plate 4. The front bottom surface of the left arm cover and the right arm cover are respectively provided with protruding posts 33. The inner side of the protruding post forms a T-shaped perforation 34 with an inner diameter greater than that in the direction opposite to the opening of the U-shaped structure. A bushing 35 is installed in the end of the protruding post with the larger inner diameter.

[0042] The arm slide 12 is an inverted U-shaped open slide or a closed elongated slide. When the arm body 3 swings up and down, the sixth horizontal rotating shaft 16 slides up and down along the inverted U-shaped open slide or the closed elongated slide.

[0043] The elastic element includes a spring 19, an adjusting bolt 20, and a connecting block 21. The front end of the spring 19 has a hook 22, which is sleeved on the outside of the eighth horizontal rotating shaft 18. The connecting block 21 is fixedly installed on the rear end of the spring 19. The stud of the adjusting bolt 20 is movably screwed to the connecting block 21. The stud of the adjusting bolt 20 can be extended and retracted into the inner ring of the spring 19. The second horizontal rotating shaft has a bolt hole 23 extending radially therein. The adjusting bolt 20 passes through the bolt hole 23, and the head of the adjusting bolt 20 stops at the rear side of the outer circumference of the second horizontal rotating shaft. The rear end of the arm body 3 has an avoidance adjustment hole 24 that is directly opposite the head of the adjusting bolt 20. Hardware tools can be inserted into the arm body 3 through the avoidance adjustment hole 24 and rotate the adjusting bolt 20. Rotating the adjusting bolt 20 can change the initial elastic force value of the elastic element. Rotating the adjusting bolt 20 can change the compression of the spring 19 in the initial state, thereby adjusting the elastic force output by the elastic element in the initial state to adapt to the stable support of displays of different weights.

[0044] The rear sidewall of the second horizontal rotating shaft in the circumferential direction is provided with a flat-bottomed groove 25 for removing meat. The head of the adjusting bolt 20 is accommodated in the flat-bottomed groove 25, and the head of the adjusting bolt 20 is tightly abutted against the flat bottom of the flat-bottomed groove 25. This can improve the smooth contact between the head of the adjusting bolt 20 and the rear side of the adjusting bolt limiting shaft 28.

[0045] The upper end of the adjustment seat 1 forms a U-shaped structure. The two side walls of the U-shaped structure of the adjustment seat 1 are respectively provided with first horizontal hinge holes 26. The rear end of the arm body 3 is sleeved on the outside of the U-shaped structure at the upper end of the adjustment seat 1. The two side walls of the rear end of the arm body 3 are respectively provided with second horizontal hinge holes 27. The second horizontal rotating shaft includes an adjusting bolt limiting shaft 28 and connecting screws 29. The bolt through hole 23 is located in the middle part of the adjusting bolt limiting shaft 28. The two ends of the adjusting bolt limiting shaft 28 are respectively inserted into the first horizontal hinge hole 26 and the second horizontal hinge hole 27. The two connecting screws 29 pass through the second horizontal hinge hole 27 and the first horizontal hinge hole 26 respectively and are screwed to the two ends of the adjusting bolt limiting shaft 28. The heads of the two connecting screws 29 are respectively pressed against the left and right side surfaces of the rear end of the arm body 3.

[0046] The adjusting bolt 20 is accommodated in the U-shaped opening at the upper end of the adjusting seat 1. The adjusting bolt limiting shaft 28 is used to limit the position of the adjusting bolt 20 on the one hand, and on the other hand, it is screwed with the connecting screw 29 to form an integral structure, which can serve as a second horizontal pivot. It is best to set a friction pad between the arm body 3 and the adjusting seat 1. By tightening the connecting screw 29, a large friction force is formed between the arm body 3 and the adjusting seat 1, which helps to position the angle of the arm body 3 and prevents the arm body 3 from swinging rapidly in an instant when the adjusting bolt 20 is rotated.

[0047] The bottom surface of the U-shaped structure on the adjusting seat 1 is a pointed structure with a height in the middle higher than the height on the front and rear sides. The screw part and head of the adjusting bolt 20 are respectively stopped on the front and rear sides of the bottom surface of the U-shaped structure on the adjusting seat 1. By setting a front and rear inclined surface on the bottom surface of the U-shaped structure of the adjusting seat 1 with the second horizontal axis as the dividing point, the adjustment bolt 20 can avoid the swing of the arm body 3 and the swing angle range can be limited.

[0048] The first connecting piece 13, the second connecting piece 14, and the support plate 4 are all U-shaped structures. The support plate 4 is sleeved on the outer side of the lower end of the first connecting piece 13, and the rear end of the second connecting piece 14 is sleeved on the outer side of the upper end of the first connecting piece 13. The elastic element is accommodated inside the U-shaped structure of the support plate 4, and the front end of the elastic element extends into the inner side of the first connecting piece 13. The rotating head seat 2 has stepped surfaces 30 formed on both axial side walls for de-meat thinning. The front end of the second connecting piece 14 and the front end of the support plate 4 are both sleeved on the outer side of the thinned stepped surfaces 30 of the rotating head seat 2.

[0049] The above structure makes the arm form a left-right symmetrical structure, which allows the fifth horizontal pivot 15, the sixth horizontal pivot 16, the seventh horizontal pivot 17 and the eighth horizontal pivot 18 to have support at both ends, so that the tension is centered. When the second connecting piece 14 moves, it also uses the stepped surface 30 of the rotating head seat 2 as the guide surface to ensure the arm moves smoothly.

[0050] The arm body 3 is also provided with an adjusting bolt guide plate 36. An opening groove is formed on the adjusting bolt guide plate 36, through which the adjusting bolt 20 passes. The bottom surface of the opening groove stops on the upper side surface of the adjusting bolt 20. The opening groove on the adjusting bolt guide plate 36 can guide, limit and support the adjusting bolt 20, preventing the spring 19 from undergoing radial deformation and causing it to wobble.

Claims

1. A constant force structure for reducing the distance between elastic elements, comprising an adjusting seat (1), a rotating head seat (2), an arm body (3), a support plate (4), and an elastic component (5), wherein the front and rear ends of the arm body are respectively rotatable around a first horizontal rotating axis (6) and a second horizontal rotating axis and are mounted on the upper ends of the rotating head seat and the adjusting seat, and the front and rear ends of the support plate are respectively rotatable around a third horizontal rotating axis (7) and a fourth horizontal rotating axis (8) and are mounted on the lower ends of the rotating head seat and the adjusting seat, wherein the adjusting seat, the arm body, the rotating head seat, and the support plate together form a parallel four-bar linkage structure, characterized in that: The front side wall of the support plate is provided with a support plate connection hole (9) and a support plate arc hole (10), and the support plate arc hole and the support plate connection hole are concentrically arranged. The front side wall of the arm body is provided with an arm positioning hole (11) and a long arm slide groove (12). The elastic component includes a first connecting piece (13), a second connecting piece (14) and an elastic element that can elastically extend and retract. The lower end of the first connecting piece is hinged to the support plate connection hole through a fifth horizontal pivot (15). The upper end of the first connecting piece is hinged to the rear end of the second connecting piece through a sixth horizontal pivot (16). The sixth horizontal pivot can be slidably inserted into the long arm slide groove on the front side wall of the arm body. The front end of the second connecting piece is hinged to the arm positioning hole on the front side wall of the arm body through a seventh horizontal pivot (17). The front end of the elastic element is hinged to the middle of the first connecting piece through an eighth horizontal pivot (18). The rear end of the elastic element is installed on the second horizontal pivot, an adjustment seat, or the inner side wall of the rear end of the arm body.

2. The constant force structure of reduced elastic member distance of claim 1, wherein: The inner side of the arm body forms a cavity structure, and the support plate and elastic components are both accommodated in the cavity structure of the arm body. The front end and rear end of the arm body are respectively formed with clearance notches. The rotating head seat and the adjusting seat can be rotatably inserted into the cavity structure of the arm body through the clearance notches. The arm positioning hole and the arm sliding groove are provided on the inner sidewalls of the left and right sides of the arm body.

3. The constant force structure for reducing the distance between elastic elements according to claim 1 or 2, characterized in that: The arm groove is either an inverted U-shaped opening groove with an open bottom or a closed elongated groove.

4. The constant force structure of reduced elastic member distance of claim 2, wherein: The elastic element includes a spring (19), an adjusting bolt (20), and a connecting block (21). A hook (22) is formed at the front end of the spring and is sleeved on the outside of the eighth horizontal rotating shaft. The connecting block is fixedly installed on the rear end of the spring. The stud of the adjusting bolt is movably screwed to the connecting block. The stud of the adjusting bolt can be extended and accommodated in the inner ring of the spring. A bolt through hole (23) extending radially is provided on the second horizontal rotating shaft. The adjusting bolt passes through the bolt through hole, and the head of the adjusting bolt stops at the rear side of the outer circumference of the second horizontal rotating shaft. An avoidance adjustment hole (24) is formed at the rear end of the arm body, which is directly opposite to the head of the adjusting bolt. Hardware tools can be inserted into the arm body through the avoidance adjustment hole and rotate the adjusting bolt. Rotating the adjusting bolt can change the initial elastic force value of the elastic element.

5. The constant force construction of reduced elastic member distance of claim 4, wherein: The rear side wall of the second horizontal rotating shaft in the circumferential direction is provided with a flat-bottomed groove (25) with a desliming structure. The head of the adjusting bolt is accommodated in the flat-bottomed groove, and the head of the adjusting bolt is tightly pressed against the flat bottom of the flat-bottomed groove.

6. The constant force construction of reduced elastic member distance of claim 4, wherein: The upper end of the adjustment seat forms a U-shaped structure. The two side walls of the U-shaped structure of the adjustment seat are respectively provided with first horizontal hinge holes (26). The rear end of the arm body is sleeved on the outside of the U-shaped structure at the upper end of the adjustment seat. The two side walls of the rear end of the arm body are respectively provided with second horizontal hinge holes (27). The second horizontal rotating shaft includes an adjustment bolt limiting shaft (28) and a connecting screw (29). The bolt through hole is located in the middle part of the adjustment bolt limiting shaft. The two ends of the adjustment bolt limiting shaft are respectively inserted into the first horizontal hinge hole and the second horizontal hinge hole. The two connecting screws pass through the second horizontal hinge hole and the first horizontal hinge hole and are screwed to the two ends of the adjustment bolt limiting shaft. The heads of the two connecting screws are respectively pressed against the left and right side surfaces of the rear end of the arm body.

7. The constant force construction of reduced elastic member distance of claim 6, wherein: The bottom surface of the U-shaped structure on the adjusting seat is a pointed structure with a height in the middle that is higher than the height on the front and rear sides. The screw part and the head of the adjusting bolt are respectively stopped on the front and rear sides of the bottom surface of the U-shaped structure on the adjusting seat.

8. The constant force structure of reduced elastic member distance of claim 2, wherein: The first connecting piece, the second connecting piece, and the support plate are all U-shaped structures. The support plate is sleeved on the outer side of the lower end of the first connecting piece, and the rear end of the second connecting piece is sleeved on the outer side of the upper end of the first connecting piece. The elastic element is accommodated inside the U-shaped structure of the support plate, and the front end of the elastic element extends into the inner side of the first connecting piece. The rotating head seat has a thinning step surface (30) formed on both axial side walls. The front end of the second connecting piece and the front end of the support plate are both sleeved on the outer side of the thinning step surface of the rotating head seat.

9. The constant force construction of reduced elastic member distance of claim 4, wherein: The arm body is also provided with an adjusting bolt guide plate (36), an opening groove is formed on the adjusting bolt guide plate, the adjusting bolt passes through the opening groove, and the bottom surface of the opening groove stops on the upper side surface of the adjusting bolt.

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